Is there a thermostat where I can set a cycle run time?

jlonj

I like to set back my thermostat temp and then wake up or come home to that strong burst of warmth when my radiators are full of steam. My old one-pipe radiators are oversized and it just feels awesome when they’re all warm. I would also think running longer cycles that fill up the radiators would also be more efficient than more frequent, shorter cycles, but maybe I’m wrong?

The problem is that I have a leak in my piping that only leaks when the radiators are full. My boiler never cycles on pressure, even when the radiators are full and the vents are all whistling. Is that normal?

Regardless, I’d like to find a thermostat where I could set my boiler to run for about an hour cycle at a time. An hour will fill up the radiators in full without triggering the leak.

I have a Nest and it’s OK but I wish I could customize it better. And the true radiant function kind of sucks and overshoots frequetly.

Gsmith

Check that the pigtail under the pressure troll is clear, not clogged. Sometimes when it's clogged you can get the behavior you describe-vents whistle but boiler doesn't shut off on pressure- that's because the boiler pressure may not be getting to the pressuretrol to shut the boiler off.

Jamie Hall

Also -- simply check the pressuretrol setting. It should be set to cut in around 0.7 psi and out at 1.5.

If a leak is the culprit in not letting the pressure rise -- which is possible -- you also need to fix the leak, as that is forcing you to add fresh water to the boiler, which will kill the boiler remarkably quickly.

Last, you don't want the boiler to keep running and raising pressure. You want it to fill the radiators so you get that nice toasty feeling -- and then shut down until the steam has condensed. Then give the system another shot of steam (turn back on) and so on, until the thermostat is satisfied. Anything else is simply wasting fuel.

The Nest has proven to be a first class pest with steam systems -- and hot water and radiant. You may be able to get it to at least not fight the system...

jlonj

@Gary Smith I had the boiler cleaned recently, and he cleaned all the pigtails and water level. So, I’m not thinking it’s clogged. Hmmm

jlonj

@Jamie Hall I have a vaporstat. What should the settings be on that?

It is a very slow leak. A few drips of water, and only when the radiators are full and (I’m guessing) when the pressure starts to build.

Fred

Where is the leak? I know we are all more concerned about the leak than we are about your original question but.....

In any case, there are timers available that you can use to set times and duration for heating cycles. I don't know how efficient they are and you don't want the boiler running for extended period to bring the house back up to temp but you are the one that has to consider what is important to you, besides fixing the leak.

jlonj

@Fred The leak is at an elbow leading up to one of the radiators. We recently had this radiator moved as apart of a renovation, and the plumber used megapress fittings. So, to get it fixed the whole thing has to be repiped

My home originally had a coal boiler, and based on what I’m reading, it’s pretty normal for those systems to generate minimal pressure? I’ve literally never seen my pressure gauge over zero or had the boiler pressure cycle in 4 years.

Jamie Hall

On the vapourstat -- I would try setting it to cut out at around 12 ounces, with a differential of 8 ounces -- that will give you a cutin of 4 ounces. That should be OK to get your radiators nice and full.

As @Fred noted, there are timers available which will cut the run off after a certain time -- but they will not (or certainly should not!) keep it running longer if the vapourstat has shut it off. Therefore, if the run time recovering from a setback is long enough to fill the radiators and shut off on pressure, they won't do much if anything for you.

You may, by the way, find that the leak goes away if you don't let the pressure build.