steam zones

mdweaver

I recently moved into a house with propane fired steam. It has 4 zones that might be original to the house which was built in 1951 but i'm not sure. I feel like having zones is inefficient because my boiler produces 2200 sq ft but is firing for only a fraction of that when only one or two zones are calling for heat at a time. very often a valve will open, my boiler fires up and then the valve closes and i have 5 lbs of pressure sitting in the pipes near the boiler with nowhere to go even though my pressuretrol is set to cut out at 1.5lbs. i think when all the valves are closed and my boiler shuts down the pressure keeps climbing for a short while because it has nowhere to go. I'm thinking of just opening all of the valves and and disconnecting 3 of the four thermostats and running it that way for a few days to see how it works. However, none of my radiators have valves that i can turn to adjust the heat. They are all convectors with covers over them Does anyone have any thoughts on zones, valves and steam heat? also, any thoughts on switching back to coal? nat gas is not available where i am. propane is expensive and i burn about 9000 gallons of propane/year.

JUGHNE

1 or 2 pipe system?
Do you have a condensate return pump or gravity?
What does the pressure run up to when most of the zones are open?
Must a zone valve be opened for the boiler to fire or does it maintain pressure?
Pictures are always helpful.
And where are you located?

EBEBRATT-Ed

I would try it without the zone valves.

You will probably need to wire 1 thermostat directly to the boiler to operate it. Run the zone valves open and disconnect the wires to the valve actuators. (you could just turn the thermostats up all the way to test out how the system runs first).

Most steam systems never had zone valves when they burned coal, the coal shovel was the thermostat.

Oil burners & overfiring lead to overheating so they put zone valves in for control.

Run it without the zone valves and see how it is. Fix the venting, control the pressure.

Once you get a handle on it you could put TRVs on the radiators starting with the ones that overheat

How about some pictures of the boiler and piping?

Once you get this working you should see fuel bills drop

mdweaver

It’s a 2 pipe system with a condensate return pump. The boiler generally fires up after a valve opens and pressure drops. But it will continue boiling even after all valves are closed until it reaches pressure. It also seems like my pressuretrol isn’t very accurate. Should cut out at 1.5 but it’s more like 3 lbs.

I’d like to run it with all valves open and just one thermostat but I’m not sure how to get all of the valves to stay open.

EBEBRATT-Ed

I could describe how to do that but on your end it requires some electrical knowledge

mikeg2015

I think there are some zone controllers that let you set the # minimum # of zones required for a call to the heating plant. I think the 4 zone Honeywell panel may have this feature. I think it still allows regular 2 wire thermostats.

Some others may as well. If your minimum # of zones calling is 2, you might reduce the short cycling. You could also add a anti short cycle timer off a separate pressuretrol. Have it restrict the boiler from comming on again after 5+ minutes or where ever you set it.

Steamhead

Are you saying the boiler maintains pressure all the time, waiting for a zone valve to open?

mikeg2015

Zone control panels also have "purge timers" so it would give the boiler maybe 1 minute to cool down a little and pressure to drop.

Other option is adding an off delay timer. So relay holds in the call for heat from the thermostat for a set time.

You also should have a anti short cycle timer on a setup like like this. So after a call, the boiler won;t restart again for maybe 5 or 10 minutes.

Steam or any type of radiant is not "instant" heat. Actually, if any HVAC system responds quickly, it's probably oversized. But radiant heat and cool down time is 30+ minutes.

JUGHNE

How about pictures of your zone valves, specifically showing how many wires go to each.
If you could get them to stay open and then have 1 tstat for the burner, that would be the first part of the experiment.

mdweaver

Here are some pics of piping and one of the zone valves.

mdweaver

also, my boiler does maintain pressure even when none of the zone valves are open.

mdweaver

One more thing. i turned up all 4 thermostats so all zones would be open and let the boiler run for 30 minutes. all of the radiators got hot without any pressure building in my boiler. is that the way it should be? i don't think the pressure was over 1lb.

EBEBRATT-Ed

There is no need to maintain steam pressure all the time. That is a "UGE" energy waste.

The zone valves need end switches wired in to control the boiler or if you don't need the zone valves leave them open and wire a thermostat directly to the boiler.

You need someone who understands controls.

Where are you located??

mdweaver

i' near wilkes barre, PA

JUGHNE

If your pressure gauge is accurate that 1 Lb would be great.
You could get a 0-5 PSI gauge to really check it out.

I have 2 old school houses with zone valves. Both had a vastly oversized boiler holding pressure 24/7. Severe overheating of boiler room and rooms above.
It was fairly simple to rewire so that only when any one zone valve opened the boiler would fire.
You could just run the smallest zone and see how the pressure reacts. Do you really need the zoning feature? Or combine 2 together and have only 2 zones total. Perhaps this would get rid of enough of the steam to keep the boiler from short cycling.

I am not familiar with your zone valves, do you have brand and model number?
Some zone valves have end switch to fire boiler.
In my case I added relays so when zone was energized the boiler circuit would close.