My steam boiler has no pressre (dosent cycle) but it heats the house.
What can be wrong?

If everything is working, heating to your satisfaction, you could have a bad gauge or a blockage in the gauge orifice.

Hi Samiamm

Residential single family steam boilers have very little pressure... can stay at almost 0 PSI until peak heat and even then, in most cases, you may only see 1/2 PSI.

As long as the boiler has the appropriate water level and you are maintaining/flushing the system and the low water cutoff (if older mechanical type) as required you should be all set here... ;)

Mark

o pressure meaning the boiler is undersized , meaning your burning 1 kw your using 1 kw , to check opertion close all valves and let is run alone with no load on it, turn on the boiler , the boiler will run and the pressure will build up until operating limit (this is your setting) I'm not sure what is your working pressure but low pressure boilers usually 1 bar or 14.5 psi, if its not working , your pressure will go higher till the safety limit trips and this is a manual reset if this is not working also your last safety will be the pressure relief valve which is set to 1 bar so your setting will be lower then 1 bar for your system to work properly

small explanation: boiler delivers 1 kw and your house load (needs)=0.5 kw so those extra 0.5kw will accumulate in the boiler water side and pressure will start rising , if u turn the boiler on 1 kw for example and your house needs 1.3kw your boiler will always run and no pressure will be build that's why I told u m your boiler is under sized

Andre

What the heck are you talking about? How can you make such a blanket statement like, "0 pressure meaning the boiler is undersized"... never mind that steam boilers don't get "valves".

You make a statement based on zero facts and then blast us with a bunch of silliness about pressure. Just how is this supposed to help anyone here... never mind that the post is from 2009??

Mark

I work on york shiply steam boilers since I was 16 , I know what I'm talking about Mr I'm an engineer not a plumber , and I teach people in middle eat what to do I work mostly on number 6 oil and number 2 oil , do you need more mathematical proof why you run your boiler and always zero I can send you a video which I can do now cheers amigo

and mr Mark the problem with this guy 0 pressure , the boiler turns off when it reach the operating limit setting? So if it stays zero when it will turn off?? The answer is never only if u turn it to off:))) when u have stable pressure while running this means your boiler isproducing steam = to the load . This is when your boiler is fully efficient , when the pressure goes up till it reach this limit this means your boiler is producing more steam that u don't need it your efficiency will go down and the extra produced steam will make pressure build up till its off :)))

Ahhh, I see... another, "engineer" that has misinterpreted a simple question about residential boiler systems. You want to talk "mathematical proof" and all we have here is a person that was wondering why the boiler had no pressure but was still heating his house.

I answered his question and you come in YEARS later and spout off a bunch of foolishness that doesn't belong in a residential plumbing forum.

Finally, MR. you asked, "so if it stays zero when it will turn off???? the answer is never only if u turn it to off". Wrong again, Mr. the answer is when the THERMOSTAT reaches temperature and shuts the boiler off!

Mark