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  • Hydronic New Shop heating??

    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

  • #2
    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.
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    • #3
      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

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      • #4
        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.

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        • #5
          Did they give a reason for not using a tankless heater?
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          • #6
            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

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            • #7
              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.
              Bart Smaalders
              http://smaalders.net/barts

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              • #8
                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.
                Last edited by kvom; 01-21-2009, 04:07 PM.

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                • #9
                  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.
                  Paul Carpenter
                  Mapleton, IL

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                  • #10
                    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
                    "Just build it and be done"

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                    • #11
                      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.

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                      • #12
                        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.
                        Last edited by gellfex; 01-21-2009, 07:14 PM.
                        Location: Jersey City NJ USA

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                        • #13
                          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.

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                          • #14
                            Wow Evan

                            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 [email protected] 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

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                            • #15
                              Wow Evan

                              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 [email protected] 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

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