Hi,

I'm new here and apologize in advance for my long posting - but I want to give all the info I have and get all my questions out there.

I've been struggling with my heating system for about a month now. First, the system was running continuously with no thermostat control. I called someone in and it seemed that the circuit had a problem. He rewired the circuit on the boiler and the system ran wonderfully.

Shortly afterward we stopped getting heat to the top floor (this is a 3 story - really 2 story with a basement apartment below, but I digress... ). I tried to bleed the radiators up there but nothing happened. I called the guy back and he noticed that the pressure was very low (around 4psi) and that the refill valve was closed. He opened it up, enabling the water to fill back into the system and pushing the pressure up. He also told me that the valve should be left open.

That evening, our tenant (who lives in the basement apartment) came home to a huge leak in her kitchen ceiling. I immediately closed the valve and called our contractor (I didn't mention that we just finished renovating the place, including moving/replacing most of the heat pipes). It turned out that the reason the pressure was low to begin with was that there was a leak in one of the pipes - it must have been leaking for a few weeks and slowly drained the system, causing the pressure to go down. When the HVAC guy left the valve open, the water just kept coming and leaking out.

Contrary to what the HVAC guy told me, my contractor's guy (who is not an official HVAC person) told me that the refill valve should not be kept open - it should only be opened to refill the system and that water shouldn't be lost and therefore there's no need for continual refill under normal circumstances.

So, my first question is, who is correct? Do I keep this valve open or shut it?

Once again, the heat doesn't seem to be reaching the top floor. I checked the pressure last night and it was at 10 psi (I assume it's psi?). I tried bleeding the radiators - nothing. I turned up the thermostat this morning and checked the pressure again - it had gone up to around 12 psi. I tried bleeding the radiators - nothing. I went down again about an hour later and the pressure was down to around 9psi. I opened the refill valve and heard water entering the system. I waited until it sounded like it was slowing down and the pressure was up to around 12 psi, and then shut the valve again.

So my other questions are: 1) is it normal for the pressure to fluctuate like that? I assumed the pressure should be constant unless there's water loss (and of course I'm terrified that the leak is still there)? 2) Does bleeding the radiator alter the pressure? If I let water into the system and then shut the refill valve when the pressure was 12psi, then went and bled the system, doesn't that cause the pressure to go back down because no new water is filling the space that the air was taking up?

Any suggestions about what order of operations I should use (or does that not matter)? Do I open valve, bleed while open, then shut valve? Or should the refill valve always be open.

Thanks in advance for your help.

If you have a auto fill valve it should be left in the auto position. This allows the system to accept additional water as needed. When the systems vents automatically or manually more room is left for more water and a minimum pressure is required to keep the system filled to the correct level for proper operation.

See this post for a bit more info.

https://www.askmehelpdesk.com/heating-air-conditioning/pressure-reducing-valve-291158.html

Hi,

Thanks for the response. I don't see a nut/bolt indicating an auto-fill valve. There is a large red contraption that is a pressure release valve, but other than that I don't see anything.

I still can't get the heat up to the top floor, even though the pressure has been sitting at 12psi all day. From the post you referenced, am I correct in understanding that I should turn the system off and let it cool before bleeding (cold start?)?

Does the pump always run, even if the flame is off?

After the system cools, should I turn the boiler back on but set the thermostat very low so that the flame doesn't come on? If so, why is this better than bleeding when the water is hot?

Thanks for suggestions!

After the system cools, should I turn the boiler back on but set the thermostat very low so that the flame doesn't come on? If so, why is this better than bleeding when the water is hot?

Not better just another option.

Does the pump always run, even if the flame is off?

Depends upon how the system is setup.

I don't see a nut/bolt indicating an auto-fill valve

It is possible you do not have one. It could be manual fill system.

I still can't get the heat up to the top floor, even though the pressure has been sitting at 12psi all day. From the post you referenced, am I correct in understanding that I should turn the system off and let it cool before bleeding (cold start?)?

It is possible your system is still air bound. The cold start is a method I have used in the past. The water will still have air/oxygen released when it heats up and still have to be bleed but it is a start point.

Your system needs some work. Auto fill valves I consider a minimum anymore and auto bleeders at the high point of the system sure do make life easy. You may end up having to call for On Site help with this one but whatever you do make sure the people you call are experienced in boiler service. To many HVAC companys have no real idea what boiler systems are all about.