Off Topic: Home heating system

[MGREEN]

My home heating system is an oil fired, forced hot water, baseboard type.
About a week ago, it was very cold and with the thermostat set
at 70 degrees, the room temp was struggling to get past 60.

The furnace would run for a few minutes and then kick off for
a little while and then repeat this cycle.
We had this behavior in the past to the point that it would
just stop running.
So a call to the fuel co. for a service and cleaning and maybe
a filter change, and we would be back in business.

This time around the service guy checked the system, and said
that everything seemed to be in order, and that due to the cold snap
we were having, that the system was having a hard time keeping up.
The water temp was set to 180 degrees and when the water temp dropped to 140 degrees the furnace would fire again, and cycle like this
as it needed to.
So he said that all that he could really do would be to set the
water temp up to 200 degrees and so he did.
That was at about 8:30AM.
The room temp got to 70 degrees at about 2:30 in the afternoon.
Everything seemed fine until this morning when the furnace kicked on
and the water in the pipes started to sort of gurgle for a little while
and then would quite down.
We turned the heat off this morning, as it was near 50 degrees outside today, and turned it back on in the evening.
When it got turned back on, it started making the gurgling again
and then got quite again as before.
I've never heard the system do this before in the 10 years
that we have been here.
I dont get what's happening with the system.
The only change is the 200 degree water temp.
It sounds like there is air in the system, but I have no
clue how it got there? Or if it is indicitave of a problem.
Anyone care to hazard a guess?
Mike Green

[Oldbrock]

It depends where the temperature control sensor is. If it any distance at all from the heat source the region being directly heated is probably reaching boiling temp and you are getting steam in the lines. Only my guess.Peter ( not my field but this came to mind )

[Bruce Griffing]

Hot water systems have something called an air scoop. The air scoop sits at a local high point near the furnace and removes air from the water. I suspect you have air in your water. This will place a significant limit on you heating capacity. This may not be the correct answer, but I would start there.

[ptjw7uk]

Did the engineer check the water pump, is it gurgleing or kettling.
Kettling occurs when the water in the system is not being circulated fast enough and you end up eith water trying to boil in the bolier.
Just a thought.
Peter

[Your Old Dog]

Our water system was so quiet you couldn't hear the pump running. You sure it is running? And what Bruce says about checking for air in the line. My system had this little bleeder valves on one end of each room. I had to put down a cookie sheet and open the valve with a wrench and screwdriver until the water came out in a steady stream to let out the air. Look for a nut with a slotted screw head in the top, that would be the bleeder valve. Had to do mine every 2-3 years.

[Bruce Griffing]

FYI, here is an air scoop:

http://www.amazon.com/Watts-Brass-Tu.../dp/B000KL7TE4

[SGW]

I think I'd check for air in the system. Do you have bleed valves on the baseboards? Take off the end covers and look for a little valve with a screw slot to open and close it. Open one up (with a cup under it to catch any water) and see if you get air coming out.

[Ken_Shea]

To add to the suggestions,
Had a similar problem a few years ago, the pump impeller/ anti toque coupling was slipping on the shaft, two set screws on this system, tightened it up and that took care of the problem. What it was doing was slipping/catching during on and off cycles.


Ken

[JCHannum]

Ditto bleeding the system to start with. Each radiator or heating section has a bleed valve, bleed them all.

If it is cycling on and off, it is one of the safety limits, not the temperature. If it could not keep up, it would run continuously.

Make sure there is enough water in the boiler, there should be a compound gauge for temp & pressure, or individual gauges. Pressure should be around 10-20PSI when not firing & around 30PSI when firing.

If the circulator pump is not working, or a squirrel is stuck in the stack, high water temp or high stack temperature limits will cause it to cycle like that.

If the expansion tank also might cause cycling if it has lost it's charge, and make it go off on high pressure. Watch the compound gauge while it is running to see what is happening when it cuts out.

[meho]

Lots of good info here. I would add that you need to check the water fill regulator/valve strainer. The bottom of the regulator should unscrew and there is screen in there. They become clogged and need to be cleaned. I clean them yearly.

Air in the system and or lack of water flow are most likely the culprets. If the water boiler is making steam you should know it. It will trip the pop-off valve, make a lot of noise and belch steam out.