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madman
01-21-2009, 06:56 AM
Well I will be getting to the Point .In my new shop I was thinking of buying a water heater unit for the in floor heating . I call a guy who helped me before with it,.(He layed out and helped me install the PEX TUBE in the proper manner with a 3 tier manifold system) He shows up with a Guy (hydronic guroo?) The guy seemed like a good guy he liked fishing I showed him some of my homemade fishing reels and my laser cut drink holders and quick release adjustable boat seat mounting system, and so on in my shop (it was COLD outside) Anyhow next thing he says is you CANT use a Water Heater in youre Garage. It doesnt meet City and Plumbing Code and all this. I say Why? He says well the city thinks that if your Water Heater in youre House ever broke downin you or the next person living in youre house might? use the one in your Garage and drink from it.(its 100 feet from the house??) (Also i will be running a 20 % Propylene Glycol Mixture with water in it) I just stood there saying squat. Then He starts talking with my Plumbing Friend (master plumber and a gas fitter) and they say stuff like heat exchanger yahda yahda ,THEN after a little while i pipe up. Hows about i lift the Hot water heater about a foot in the air so when theres gasoline on the floor? It wouldnt maybe blowup from the open pilot flame on the water heater? I got some funny looks then the Guy says well we could use a Tankless water heater unit, Its Small compact, It would mount up on the wall and would easilly heat youre 22 by 24 foot shop with 750 feet of 1/2 Pex Tubing imbedded into the concrete floor. Wow was that a long bit of typing. Im thinking UH well its still a water heater why now is this OK and not with water tank heater unit? Well Guys what you think> Is this a viable way to go Tankless water heater unit for floor heating>?>???? thanx Im scared how much it will be I never even asked. It is cold and I need Heat NOW thanx Mike

Evan
01-21-2009, 07:07 AM
I didn't have a chance to discuss the cost with you last night because you were busy but the cost of a NG tankless system will be around $1000 or so not including any other parts of the installation. If it costs much more than that for the heater then it isn't a good deal. Systems are available here for around $600 for a 80 amp electric heater that will serve whole house to NG units that sre somewhat higher because of venting considerations. I considered going for the demand heater but power is a possible problem. I would have to give up one of my 230 circuits in the shop to run it. Natural gas isn't an easy option because of problems meeting code for the venting.

spkrman15
01-21-2009, 07:10 AM
Mike,

Around here they do not encourage using the water from your residential hot water tank to heat your floor. The reason is you could get contaminants in your water that will make you sick. Remeber Concrete is pourous, so that oil, gas or water you spill will seep down. A small hole in your pipe and now you have oil in your water system.

That is probably when the subject of a heat exchanger came up. I am not a fan of those, just because you are always losing efficiency when you transfer heat.

I have heard positive things about those in line hotwater heaters. I have never installed one, but they are compact and only run when they have to. But when they run...WATCH the meter turn!

I would go for a seperate hotwater tank. Use it just for your shop. That is my 0.02 but i have no knowledge of yoru building codes.

Rob :)

kvom
01-21-2009, 07:22 AM
I have an electric water heater in my garage (7000w) and it is doing a good job of heating my 25x36 shop. I installed an "open direct" system: it uses potable water that also serves the upstairs bathroom plus my shop sink.

The supplier of my system recommends a gas-fired boiler, but since I don't have/want gas supply to my shop I went with electric. They also counseled against the tankless heater.

Since you want a closed system it's hard to imagine that anyone would worry about drinking from it. I would check with the plumbing inspector about local codes.

Evan
01-21-2009, 07:31 AM
Did they give a reason for not using a tankless heater?

PackardV8
01-21-2009, 11:01 AM
A small hole in your pipe and now you have oil in your water system. The water in a heating system is always under pressure. First, no way is a soil contaminant going to seep into a PEX tube and second, water pressure would send water out into the concrete. I suppose one could imagine an end-of-world scenario where the water supply lost all pressure AND the last water in the area was in that tank AND there was a pool of gasoline in the concrete AND there was a hole in the PEX AND the electricity was still on to the pump. However, my pump is above the tank and would lose prime if there was a leak with no incoming water, so I can't see any likely way contaminants could enter the system

I have used both a regular NG hot water heater for the floor and a 65-gallon dual outlet unit which serves residential hot water and heating system. It cost about three times as much as the standard hot water heater, but is supposedly better built. Make sure your heater is in your heated space. Then, the tankless unit is moot. Any heat loss from the tank just becomes heat for the space it is heating anyway.

Bottom line, I love radiant hot water heat in the floor. Any residence or shop I build WILL have it. If the code permits and you have it available, use a regular NG heater - venting is easy and inexpensive.

thnx, jack vines

barts
01-21-2009, 11:43 AM
When (if, sighs looking at 401k) I retire I'd like my shop to have hydronic heat... since our place in the San Juan Islands has ten acres of almost all woodlot, wood heat seems like the way to go as energy costs are bound to continue going up after this 'session is over - and wood heat is free and reasonably green in an area w/ plenty of fresh air... I've been thinking about a wood-water heat exchanger that would heat the glycol/water mix in the floor; the commercial units are much larger than I would need for a 1000 sq ft heated space. Having built the boiler in our 19' steamboat, this seems like a tractable problem; the most tricky aspect seems to be not mis-behaving when the power goes out . The approach I feel most comfortable with involves having the tank & pump far enough below the stove that the glycol mix will drain back down into the tank (backwards through the centrifugal pump) when the power is off. The pump motor would be under manual control; it could auto shut off whenever the temp. at the stove dropped below 100F or so... clearly there would need to be room for "air" in the tank, and a vent line from the top of the heat exchanger back down to the top of the tank so that oxygen wouldn't get replenished in the glycol mix to cut down on corrosion. W/ an appropriate safety valve and steel heat exchanger, this would seem pretty fool-proof; the manual restart requirement should prevent a power failure from causing cool glycol from hitting hot heating surface and generating steam when the power came back on.

kvom
01-21-2009, 02:58 PM
Did they give a reason for not using a tankless heater?
Radiant needs a fairly large quantity of warm water, while tankless heaters deliver smaller quantities of much hotter water. I believe that's the main reason, although it is possible to plumb a tankless heater with mixing for hydronic. It's just more complex.

My water heater is typically outputing 120F water into the floor.

My costs for a 36x25 slab were:

$1100 for PEX, 4 loop manifold, thermostat, pump, controller, mixing valve, pressure release valve, all shipped as a pre-designed unit.

I laid the Pex myself before the slab was poured. The PEX was 3/4" and I laid only 3 loops. 5/8" in 4 loops would have been easier in retrospect.

I spent $300 for a 7500w 220v water heater, and paid a licensed plumber ~$700 to hook up all the piping (it was one part of plumbing the entire shop and apartment).

I wired the controller, thermostat, controller, and pump together myself.

pcarpenter
01-21-2009, 05:04 PM
I know this is not the dissenting opinion you may want to hear, but I abandoned the in-floor radiant heat thing for my shop due to time constraints and am glad I did.

I found that my shop use is sometimes quite sporadic and that is not a good case for the hydronic heating method that only makes sense by keeping the water warm all the time and heating all the time (if I were keeping it warm with radiant heat). Out of the 168 hours in a week, I may be there 16 or so which means I am pumping heat into an otherwise empty building 90% of the time. IN my case a slightly oversized forced-air unit heater lets me bring it up to temp in about 20 minutes-- not something you can do with radiant heating...and definitely not without keeping the water hot all the time. It never gets below freezing due to some radiant heating through the windows so I am typically bringing it up from maybe at the lowest around 34F to about 57F where I like it.

Last winter I used about 75 gallons of the 200 gallons of LP I had delivered. There is no way I could do that if I were heating it 900% more (time) than I was using it.

I realize you may be in your shop more than I ever will, but you will still have to evaluate the wisdom of a system that means you are heating the shop 24x7.

tiptop
01-21-2009, 05:18 PM
I use hydronic heat in my house and a 40 gallon water heater for it. I put tubes in my shop addition and will use a tankless heater and a wood fired boiler to heat it. I do not know how well a tankless heater will do by itself. Jay

Evan
01-21-2009, 05:52 PM
Madman (Mike) makes his living out of his shop and works there daily so it is probably a good case for 24/7 heat with a setback for overnight. I don't think Mike will mind if I post a picture of his new shop space. This is what he needs to heat.

http://metalshopborealis.ca/pics5/mikeshop.jpg

gellfex
01-21-2009, 06:11 PM
While I love the hanging pex radiant I put in my kitchen and bath, I agree with pcarpenter about radiant being better for residence than shop. I'd hang one of those Modine gas heaters from the ceiling and call it a day. My old loft shop was 25 x 90 with 12' ceilings and had 2 of those heaters keeping it toasty.

My current shop has a 40k btu ventless blue flame heater helped by the heat loss of the boiler and water heater. It's crazy efficient, like 99%, and adds humidity too. This old place isn't tight enough to worry about winter rust from that.

BTW, if you're not embedding the pex, you can run 180 deg water right from a standard hydronic boiler. I just added it as another zone, no fancy manifolds or heat exchangers.

jdunmyer
01-21-2009, 06:22 PM
One of the supposed concerns was (the way I read Mike's message) that someone might remove the water heater that he wants to use for his shop heat and install it in the house. That seems unlikely, and should be of no concern.

A tankless water heater has no advantage for shop heating purposes, in fact, they're not all that great in saving money for domestic hot water, according to what I've read. Their big advantage is eliminating the tank of hot water that is losing heat to the air, even when you're not using any hot water. In actual practice that heat loss cost is overblown, a modern water heater doesn't use all that much energy to keep itself warm. I've shut the water heater in my shop off for extended periods and have never seen a noticeable difference in my bill.

The concern about lag time in getting the shop up to temperature is valid for some, but if Mike is in his shop most of the time, it's probably not a big deal. Warm floors are worth something, too.

madman
01-21-2009, 07:34 PM
Howd you do that HA HA LOL> Ilike that Picture. I guess my Shops Famous Now HAHA> I was in there all day and i have two other shops on the other side of my House. I was working on my Insulation R@22 and vapour barrier and then the plywood (1/2) inch wall for the hot water gizmo the Plumbers are going to install i hope tomorrow,.(they need a place to mount it Im giving them a wide area in case they want to dinkl around and move it around a few times LOL) I had a 350,000 btu propane heater going for 5 hours and it didnt even warm the damn place up. I think the propane salamander heater is plugged up a bit. (I looked for my tip cleaners but couldnt find em Im just gonna jam a drill through the orifice holes size of orifice is actuiually given on the metal plaque on the heater unit) I hasve since finished the shop with a custom insulated 2 inch door double security latches and strips of stainless steel wwith hundreds of fish hooks everywhere waiting to snack some stupid dirt bag who tries to rip me off. Ill get Moose to gnaw on his ass a bit before i call the fuzz Later MikeAnyways thanx Evan Mike

madman
01-21-2009, 07:34 PM
Howd you do that HA HA LOL> Ilike that Picture. I guess my Shops Famous Now HAHA> I was in there all day and i have two other shops on the other side of my House. I was working on my Insulation R@22 and vapour barrier and then the plywood (1/2) inch wall for the hot water gizmo the Plumbers are going to install i hope tomorrow,.(they need a place to mount it Im giving them a wide area in case they want to dinkl around and move it around a few times LOL) I had a 350,000 btu propane heater going for 5 hours and it didnt even warm the damn place up. I think the propane salamander heater is plugged up a bit. (I looked for my tip cleaners but couldnt find em Im just gonna jam a drill through the orifice holes size of orifice is actuiually given on the metal plaque on the heater unit) I hasve since finished the shop with a custom insulated 2 inch door double security latches and strips of stainless steel wwith hundreds of fish hooks everywhere waiting to snack some stupid dirt bag who tries to rip me off. Ill get Moose to gnaw on his ass a bit before i call the fuzz Later MikeAnyways thanx Evan Mike

hardtail
01-21-2009, 08:36 PM
I would not go the tankless heater route, those burners are sized 2-3X's the output of a standard heater for there instantaneous demand use, having a continuous demand is going to mean lots of cycling with a big burner totally opposite design for this application, slab heat requires dedication once the heat cycle starts, in fact it would be good to have a relay or timer circulate your medium 5-10 mins every hour even if your t stats aren't calling for heat.

I would go the standard heater route, they don't posess near the efficiency as a boiler designed for this use but then they don't carry the big price tag either. In AB the codes are you can't use a DHW tank for primary heating, with some song and dance you might mention a wood stove is the primary and the heater secondary and after the inspections are signed off do what you really want to.........

Edit: Correction, here now the codes want an air exchanger that is classified as your primary heat source, floor slab can be secondary, their reasoning is the houses being built now are so air tight fresh air must be brought in for all that is going out but I didn't know if it had made it's way down to shop construction so you might dream up some simple air handler to satisfy their requirements and put your good ol floor tank in, just be careful if you have propane tanks inside...........when I built I had to have the air handler but there was no requirement that it ever had to be used.

madman
01-22-2009, 08:57 AM
I was all set to do a hot water tank system Now im getting nervous., i cant afford a Heater going steady forever? LOL I was tiold by the Plumber and Hydronics guy that The city was worried(NOT ME) about someone hooking into the Hot Water Tank for drinking weater? I add that 20 percent glycol will be added to it. Im starting to think i made a big mistake putting in this pex tube. Thanx

gellfex
01-22-2009, 09:38 AM
I was all set to do a hot water tank system Now im getting nervous., i cant afford a Heater going steady forever? LOL I was tiold by the Plumber and Hydronics guy that The city was worried(NOT ME) about someone hooking into the Hot Water Tank for drinking weater? I add that 20 percent glycol will be added to it. Im starting to think i made a big mistake putting in this pex tube. Thanx

If that's really the only issue, a $500 heat exchanger will eliminate it. It's like 6x6x48, and you have a circulator running to it from the tank, and another circulator for the pex. I'm not certain, but by doing this and setting the exchanger thermostat to 105 or so, you may be able to eliminate a bunch of other expensive mixers and controls you would have needed.

slugger
01-22-2009, 11:15 AM
Dude- don't listen to all the nay-sayers. A tankless will work just fine. I know a lot of folks that use them including me. I bought three when I built this house last year. Mine are all Rheem natural gas fired units. One is dedicated to HRFH (Hrydonic Radiant Floor Heating)

Just make sure your recirc pumps is big enough to demand enough water to fire your heater. I have a closed system. Nobody is going to tap into it for hot water. That is about the silliest thing I have heard.

Set your thermostats and master control so that it doesn't cycle too much. It's nice in that it keeps the machines at a constant temperature so they hold tolerances better.

I paid only about $600-$700 a piece for each of my three units. They are like 7.4 gal/minute models. The stainless steel vent pipe is expensive though- probably another $250 just for that! I good 75 gal tank heater is this much or more but can use standard stove pipe for venting.

I had to put a light bulb and a line voltage t-stat in my closet so that they won't freeze up on cold nights as they sit dormant. One is in the garage and doesn't need any protection.

In a perfect world, you are supposed to use a boiler but that is overkill for your application. Some Tankless units are rated for floor heat, some aren't. Mine are NOT and work fine.

tony ennis
01-22-2009, 11:31 AM
I don't know if this is the same thing or not, but our scout troop had the use of a large concrete block building. It was heated by hot water and old-fashioned wall radiators. Nothing in the slab. I was surprised by how quickly it heated the space up. When we left for the evening we'd turn the heat down to 50.

gellfex
01-22-2009, 11:53 AM
Dude- don't listen to all the nay-sayers. A tankless will work just fine.

It seems the issue for Madman is less what will work or not and more what the inspectors will approve. We all know a simple water heater WILL work! One of the radiant gurus at Radnet http://radnet.groupee.net/eve/forums recommends them as better since they're very efficient when run at low temps. At least around here, inspectors know nothing at all about radiant, get no training on it, and are free to make up regulations on the spot.

madman
01-22-2009, 01:21 PM
The photo Evan Posted of my Backyard Shop, the small building on the right is where I sleep and Eat>

kvom
01-22-2009, 07:57 PM
The inspector who came out for my rough plumbing inspection took one look and said, "this is non-standard" and said I needed to talk to his boss. I emailed him the URL of the website for my supplier with the details of the system I had installed. When the chief came out he had reviewed the info and passed the setup. You might want to do the same in advance.

Of course you could just wait until the rest of the building is approved and add the hydronic later.

As for the old-fashioned radiators, they require very hot water and hence a boiler setup.

keelan
01-22-2009, 08:10 PM
Mike,

Would it make them feel better if you painted the tank bright orange, replaced all the fittings with metric left-hand threaded ones, put a big skull and cross-bones on there, and dyed the water green? Maybe mix something with the water to make it smell bad as well.

:)

hardtail
01-22-2009, 08:48 PM
It seems the issue for Madman is less what will work or not and more what the inspectors will approve. We all know a simple water heater WILL work! One of the radiant gurus at Radnet http://radnet.groupee.net/eve/forums recommends them as better since they're very efficient when run at low temps. At least around here, inspectors know nothing at all about radiant, get no training on it, and are free to make up regulations on the spot.

This is good advice, my local inspectors proved to be valuable resources at times, finding out what the basic requirements are up front may help you plan your course???????Gellfex has some good advice on saving some $$$'s on controls as well. The radiant heat was a good idea and your gonna love it in the long run........

carlquib
01-23-2009, 10:47 AM
This is a very timely thread. I am going to expand my shop this spring and am planning on putting floor heat. Right now my shop is 40 x 60 and heated with radiant ventless propane heaters. They work very well for the rest of the shop but are hell on my machine tools. The shop almost never freezes but it will drop to 36-40 overnight depending on how cold it is outside. When I come in and fire up the heaters it is comfortable in 15 minutes but all my tools start to sweat and it has been a constant battle to keep bright metal bright. I am planning on a 15 x 60 addition to put the machine tools in. I am going to super insulate R28 walls and R42 ceiling and then use a water heater to maintain the temp at a constant 60 in the winter. I was counseled by my builder to use a tank water heater so I didn't have to have a separate expansion chamber. As someone else mentioned when you run a tank water heater output temp is only between 100 and 120 degrees. My unit will be electric, supposed to be more cost effective in my case than a vented gas unit all the lost heat loss is in the shop. I am going to put some high density 2 in foam under the floor too. My brother inlaw was telling me about insulating concrete that they use but I haven't been able to find anyone locally that does that. Are there any better options to insulate the floor. The foam is what my builder recommended, but I am worried about the concentrated load from the tools. I am planning on a 6 inch slab over the foam with the tubing embedded in the concrete.

-brian

barts
01-23-2009, 11:01 AM
Brian, take a look at the following:

http://www.nfstyro.com/Building_Materials/ins.html

You want 1 or 2 inches of EPS foam under the slab....

- Bart

gellfex
01-23-2009, 11:14 AM
Brian, I would run the numbers on gas vs electric carefully. I'm not as familiar with propane prices, but in the NE electric can't come close to gas as far as btu/$, even accounting for no flue losses.

That radnet forum I linked is a wealth of info with some knowledgeable guys, worth a look.

carlquib
01-23-2009, 12:03 PM
Thanks Bart I will look into that insulation.

Gellfex, I am in southern Idaho most of our power still comes from hydro so it is pretty cheap in comparison to the rest of the country. I have problems with local code too when trying to put a gas heater in a shop. It would have to be in a separate isolated room. My local builder also says that the electric in a mostly closed system, like I am planning, will last longer than a gas unit. I am relying on his experience with these systems. Supposedly they have done quite a number of them so I hope he knows what he is talking about.

-brian

gellfex
01-23-2009, 12:27 PM
Thanks Bart I will look into that insulation.

Gellfex, I am in southern Idaho most of our power still comes from hydro so it is pretty cheap in comparison to the rest of the country. I have problems with local code too when trying to put a gas heater in a shop. It would have to be in a separate isolated room. My local builder also says that the electric in a mostly closed system, like I am planning, will last longer than a gas unit. I am relying on his experience with these systems. Supposedly they have done quite a number of them so I hope he knows what he is talking about.

-brian

Ah, I didn't look at your info! I'm jealous, I haven't been to Idaho to kayak since 97. There's some amazing rivers there.

slugger
01-23-2009, 05:17 PM
My cousin has gone through 2 electric units in 2 years. They keep burning up from working so hard. His gas one, a Rinnai is fine. I was going to go with Rinnai or Noritz but the local supply house started carrying Rheem and they had good reviews- that the direction I went.

I guess I don't understand your code issues. Do you already have a building permit? Have you already submitted plans? If this is a work in progress, you can always file an addendum and show the heating plans.

I didn't show my floor heat on my plans and didn't ask. I just put them in and went to town. I had hell for inspectors too. It wasn't an inspection item. There are some gas appliances that are ventless and others that are not. If you get one you can mount on an exterior wall, it will be similar to an RV water heater with the grill outside for getting oxygen and venting excess heat off.

Mine couldn't be mounted this way so I have these fancy ass stainless steel vent pipes. I originally sized it for a certain size heater and the plumbers installed them. Then they found that they only had 3" vent pipes on them. There were no 3" vent pipes in stock so they switched me out to bigger units for free so that I could use the 4" vents pipes they had in stock.

If you haven't submitted plans yet, just write on there what you are going to use. If they approve it great! If not, see what is required.

To me, one of the biggest virtues of the tankless heaters are the small space they require to install compared to tanks. I have NO expansion tanks in my systems (culinary water) and they work fine. My previous house (rented while building this one) had a 60 gallon tank type and it required an expansion tank.

Another nice thing about floor heating is that it is even. No hot spots and no cold spots. If you are cooling down to 36 every night, a floor heat system in NOT for you. They only work if they are maintained. I wouldn't let them cycle off too much at night- certainly not more than 10 degrees. They are something that you can switch on and have instant heat. You need a high BTU furnace for that.


http://i68.photobucket.com/albums/i21/dennisinaz/heaters1.jpg

http://i68.photobucket.com/albums/i21/dennisinaz/venting.jpg

http://i68.photobucket.com/albums/i21/dennisinaz/t-stat.jpg

carlquib
01-23-2009, 09:53 PM
Slugger I assume some of your post was aimed at me so let me try to answer some of the questions. My shop now is only moderately insulated, if you look at my posts I am planning on insulating the new addition so I can maintain the temperature in the machine shop, no more wild temp swings. Another goal is to separate the machine tools from the dirty fabrication side of the shop. It is always a fight to keep stuff clean as I bring machinery in and out all year long. I don't know a lot about this heat other than a friend has it and I like it, floors are always warm and temps stay very constant. I am looking at a standard industrial tank water heater so I expect it to last for 10 to 12 years. The ventless tankless water heaters don't make sense in my case. If the builder has his numbers right and I assume he does, this isn't his first go with this heat, the tank heater is the cheapest best long term option. The system is designed so that a pump circulates the water according to heat demand. The water heater is set to maintain a water temp of about 115 and an air temp of 60. My builder said hotter water will cause problems with the concrete.

-brian

slugger
01-25-2009, 06:24 PM
I agree with most of that, but unless you are putting the WH inside the room you are heating, you are wasting a lot of energy keeping some other place warm.

I can't imagine a situation where a tank-type WH would be better for this than a tankless. I thought they were a lot more until I priced an bigger tank. My gas bill is 1/2 of what it was in my previous house which was smaller but had a tank heater with a re-circ pump. The house was brand new and supposedly had good insulation.

Good luck with your system. I guess guys like to use what they are familiar with and this may be the case with your builder.

gellfex
01-25-2009, 09:45 PM
Slugger,

The point is that since he needs 100 deg water not 140, and it gets recirculated because that's the nature of hydronic radiant heat, he'd have to have a tank anyway if he had a instant heat system. If you use 140-180 water there's fancy 4-way thermostatically controlled valves that bleed in hot water to the loop while draining cool water back to the tank.

I was told that water heaters when run cool are very efficient, their radiant heat loss from the tank is much lower than when run at domestic water temps, and their life extended.

slugger
01-26-2009, 09:23 AM
You can set the t-stat on the tankless at any setting you want up to 120, after that you have to enter some by-pass codes and can go on up to 140.

I think you can run up to 110 in a slab with no ill effects. Don't know about the efficiency of running a tank-type at low temps. Should make no difference. I don't see why he would need a tank- I have seen a lot of tankless RFH systems and none had more than a small expansion tank.

A recirc pump, small expansion tank and a control box are all that's needed beyond the tubing and manifold. I have seen systems without t-stats as well. They are manually regulated and simply turned on and off. You can make these as complicated as you want.

madman
01-27-2009, 07:08 PM
I plan on leaving my heating system at 50 degrees forever? I also already have the guys coming and can hardly wait. Its cold up here. I need heat so i can take on some more work for my new little shop. I think the commercial tankless system will be good and i was told the way the guys are setting it uop will use one third the gas of a reg water heater type hydronic system. I will post pictures when completed and or will get someone who knows how to do it to do it for me thanx all for the tips Mike (-16 today)

tiptop
01-28-2009, 07:44 PM
Mike,

I posted a little earlier in the thread. After reading on since then, here are some of the design criteria I ued when building my system. as I stated earlier, I used a gas fired 40 gal HW heater. The system works like this; Thermostat does not call for heat, The HW heater exhaust fan switch is not made, no hot water, the thermostat calls for heat, the fan exhaust fan switch is made, recirc pump comes on, heater produces water, thermostat satisfied and shuts down the heater and pump. It works very well, I heat with 90 degree water, the heater, the pump, expansion tank, backflow valve and manifolds are below in the basement, also heated. I would not use any thing else for heat and am very interested to see how well a tankless heater will operate. What is your average degree day? What part of the country do you live in?

Jay

Your Old Dog
01-29-2009, 07:52 AM
And from afar and high up in the peanut gallery comes this:

Put in a two furnace system. Use an overhead gas fired unit for quick heat and turn on the hydroponic system at the same time. Once it's up to temp the hydroponic should take over and give you some great heat to work in. This of course if heating it round the clock is not cost effective. My shop heat is turned off after 4PM and I turn it on in the morning when I take the dog out. 30 minutes later I'm in my T-shirt.

hardtail
01-29-2009, 08:21 AM
YOD either your reply is a play on words or you've been to BC........smile..LOL

I have the 2 part system also, I run the floor at a lower temp constantly with one Tstat and a fan coil unit off another when you want it warmer.

Your Old Dog
01-29-2009, 08:37 AM
YOD either your reply is a play on words or you've been to BC........smile..LOL

I have the 2 part system also, I run the floor at a lower temp constantly with one Tstat and a fan coil unit off another when you want it warmer.

I've been told it's more efficient to run two furnaces in a home environment. One that runs 24-7 and one that kicks on when the prime one can't keep up. Most in-efficiency is in heating up the flues to get the furnace up to temp and then heating up the heat pipes to give you warm air in the living room.

tiptop
01-29-2009, 09:19 AM
YOD,

This is an interesting thought. I had not considered it when designing and installing my house system as everything is in the basement that is heated as well. My HW heater is supplying 90 degree water and it does not cycle long to heat the floor and then of course the thermostat. I do have temp gauges on my supply and return lines. When the system starts, the return water is usually at 65 degrees, I never considered this jump from 65 to 90 degrees to be a problem as the heat used to achieve it has in the house, but with todays energy costs the picture is changing.

Jay

kvom
01-29-2009, 11:42 AM
I think there is a significant difference in hydronic heating from slab buried PEX and floor heating using conduction plates. The slab has a large thermal mass and can take significant time to raise the temperature.

OzHeat
01-30-2009, 04:22 AM
Madman,
I think the code issue has to do with the glycol that you would use in a storage HWS.

The people who write your code in the states are worried that you or someone else would use the once contained glycol heater for potable water.

I'd be even surprised you could use an instantanous (tankless) HWS with a glycol mix as it would have the same issues but these are easy to flush out.

I could be wrong as I am from Oz and here we have distinction between hydronic and potable water heaters. We have also some of the most stringent plumbing codes in the world.

madman
02-04-2009, 04:30 PM
Well its mounted and waiting for the Gas Fitter to come, Soon I shall be wallowing inside my heated new shop i comfort. I can hardly wait .Today i was outside my old shop with my large machinery moving pry bar chipping away big chunks of ice so i can open the door bought minus 14 outsied well i ended up getting >? ?Frostbite or actually burnt??my small finger. Man im getting sick of winter crap. LOL Take care ill send some pictures .

madman
02-05-2009, 04:11 PM
Yup it was -29 this morning, The gas guy still didnt come but for a few minutes earlier this week to look at what they (yup 2 of them) needed for the final installation. (I was thinking why not bring a few more of youre friends so you can jam me for more money eh?) anyhow He said thursday or Friday and well its thursday not here yet maybe Friday . I sure hope so. I will post some pictures when i get my Camera figured out. Evan was so okind to offer to help me one evening and had even phoned me but i had company from out of town and couldnt get to my computeer. I have also been very busy. I hired a employee to work in my shop and he is good. I wanted to hire Dave Coffer but he doesnt wanna live in the Arctic. LOL Mike