Pressure Loss In Furnace

Reply

  #1  
Old 01-28-12, 06:00 PM
Member
Thread Starter
Join Date: Jan 2012
Location: usa
Posts: 2
Received 0 Votes on 0 Posts
Pressure Loss In Furnace

Hey guys, I need some help with my furnace. First off, I've read a lot on these forums and I know a little about boilers so I'm off to a good start and have gotten far. Plus I'm a Volvo technician so mechanical ability is not something you will be fighting lol. Ok, so first things first I have an oil-fired Slant/Fin Liberty L30PT with a Fill-Trol expansion tank system. My home is single zone heated. My initial problem was no heat in the top floor and poor hot water pressure in the upstairs shower. I checked the pressure in the furnace and there was hnone. I cheked the pressure in the expansion tank and there also was none. I filled the expansion tank to 15 psi, the pressure gauge on the boiloer was reading the same as my tire gauge so I believe it to be accurate. This fixed the heating problem and the hot water pressure improved. As of today heat and hot water are still working fine. I checked the pressure in the furnace and it was down to 10 psi. My new issue is nailing down the pressure loss. I checked the furnace area for signs of water leakage. On both blow off valves there was water trickling down from the caps. I know that the caps are supposed to be loose to alolow for pressure relief. My question is if I can tighten these caps down until I change the valves or is this condition normal when repressureizing the system. Also, should I repressureize the expansion tank? All help would be appreciated.

Nick
 
Sponsored Links
  #2  
Old 01-28-12, 06:23 PM
Member
Join Date: Aug 2009
Location: USA
Posts: 4,947
Received 0 Votes on 0 Posts
I think you may be confusing air vents for pressure relief. Pressure relief valves do not have screw caps.

You should only be checking and adding pressure to your expansion tank when the boiler pressure is at 0. There is a possibility that you tank is shot. Did any water come out of the valve when you checked the pressure on the tank?
 
  #3  
Old 01-28-12, 06:29 PM
Member
Thread Starter
Join Date: Jan 2012
Location: usa
Posts: 2
Received 0 Votes on 0 Posts
Thanks for the correction. I wasn't too sure what to call them. I'm not too versed on furnaces. The boiler pressure was 0 when i filled the tank. I did know about the bladder inside the tank so i looked for water, and none came out. I also did a tap test on it to check for water in the air half. It passed the test. Neq question- should water come out of those air vents?
 
  #4  
Old 01-28-12, 09:16 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 3 Votes on 2 Posts
Fill-Trol expansion tank system
First, this system is a bit different than a 'normal' expansion tank. You can NOT replace that tank with one off the shelf from HD or Lowes because the tank itself is DIFFERENT. There is a 'push-rod' built into the tank that operates the fill valve. See:

The product brochure can explain it better than I can...

http://www.amtrol.com/media/document...ILLTROL_IO.pdf

The 'tap test' in my opinion is useless. Unless you have a tank there full of water and one that is empty, how are you to know the difference?

I'm not saying that yours is conclusively bad, but I do have my doubts about it.

Since the air charge in that Fill-Trol is what controls the system pressure directly, and the minimum pressure in the system 'tracks' the air charge on the tank, if it has dropped to 10 PSI in the system, it means that the tank has also lost some of it's air charge. It could be as simple as a leaky Schrader valve... check it with some soapy water.

The automatic air vents should not have water leaking from the vent. They need to be replaced.

My question is if I can tighten these caps down until I change the valves
Since their sole purpose is to vent air from the system, if you don't hear air gurling around the piping when the pump runs, then you don't have any appreciable air in the system anyway. So yes, you can close the caps until you have a chance to change them.
 
  #5  
Old 01-28-12, 09:24 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 3 Votes on 2 Posts
Further:

The pressure in the boiler should and will have absolutely ZERO effect on the pressure in the shower. The two systems are completely and totally separate.

So this:

This fixed the heating problem and the hot water pressure improved.
is a figment of your imagination.

IF your boiler also heats the domestic hot water in the home, the boiler can be responsible for not enough hot water, and if the coil in the boiler that does the heating becomes 'limed up' with mineral deposits, it can also cause low pressure on the hot water. But the pressure in the shower can in no way be remedied by raising the water pressure in the boiler any more than the oil pressure in an engine can remedy low fuel pressure.
 
  #6  
Old 02-09-12, 12:39 PM
Member
Join Date: Mar 2008
Location: Pennsylvania
Posts: 40
Received 0 Votes on 0 Posts
I am also having water pressure issues. I have an older Weil Mclain and I've noticed my water pressure going down. The pressure indicator on the furnace is reading very low, as in very close to zero. Since the decline in water pressure seems to have been gradual, would this point to the heater coil being "limed up" with deposits? Is there a fix or must the coil be replaced.

I have someone coming to look at it but I'd like to at least try to be a little informed. Thanks in advance for any thoughts/advice.
 
  #7  
Old 02-09-12, 03:50 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Received 3 Votes on 2 Posts
Water pressure issues... where? You mean domestic water pressure? Just the HOT or the COLD also?

I presume that you know that your domestic hot water is produced by your boiler? In other words, you don't have a separate hot water heater?

If so, then yes, a gradual decline in the HOT WATER PRESSURE ONLY, could point to the domestic coil in the boiler being limed up.

If you also have low pressure on the COLD water supply, then you've got another issue altogether.

Yes, there is a process where the technician will attach a pump to the coil and pump an acid solution through the coil to 'boil' out the mineral deposits. If they aren't already installed, he will have to cut some pipes and install some valves to enable him to do so.

The low gauge reading on the boiler is another separate issue which should also be addressed. The reading of the boiler pressure gauge has NOTHING to do with the domestic water pressure. It's a totally separate system. The domestic hot water coil inside the boiler is totally isolated from the boiler pressure.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: