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Rick
Rick, HVAC Supervisor
Category: HVAC
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Experience:  40+ yrs. experience as a licensed oil & gas technician.
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The heat in my apt isnt working. I have a late 1980s Slant

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The heat in my apt isn't working. I have a late 1980s Slant Fin 100 series gas fired boiler. The water pressure is less than 10lbs. I know that it should be between 20-30lb. I opened the valve going into the expansion tank/boiler, but nothing happened.

Would you know how I can increase the water pressure?

Rick :

Welcome, my name is XXXXX XXXXX I will do my best to help you with your issue.

Rick :

The water pressure won't keep the burner from firing. Is the water in the boiler hot?

Rick :

20 to 30 psi (30 psi is max) is what the pressure should be when the water is hot. Unless you live on the 3rd floor 10 psi is ok when the boiler is cold

Rick :

So we need to figure out why you don't have heat. Is it because the burner is firing so the water isn't hot or do you have air in the lines so the water isn't circulating

Customer: Hi, Rick. I live on the 4th floor (the pressure dripped
Customer: Hi, Rick. Thanks!!!! I live on the 4th floor so 10 (now 5) is probably too low.
Rick :

Ok then if you're on the 4th floor and the boiler is in the basement then 10 psi is too low.

Customer: The boiler is hot. No water seems
Rick :

You need to find the cold water pipe that feeds the boiler.

Customer: to be reaching the apt radiators (I opened those valves and no water or air comes out)
Rick :

The valve between the boiler and expansion tank should always be open

Customer: Ok. I see two pipes going into the tank and boiler
Rick :

The cold feed line will probably have a feed valve on it. This device regulates the water pressure let into the boiler. I'll try to post a picture or a link to show you what a feed valve looks like. Give me a minute

Rick :

You may have a different brand but they are all similar

Rick :

If you can find this device we can probably put it on bypass/fast fill and bump up the pressure

Customer: It's on a pipe going directly into a pipe on the expansion tank
Customer: Ok, I see something similar, but it has a hexagon bolt on topShould I use a wrench to unscrew it?
Rick :

What color is it?

Rick :

you're sure it's on the water line that feeds the boiler and not on the water main for the bldg.

Customer: Gold bell shape like your pic. Silver bolt going into the bell that I can open with a wrench. I can send a pic...
Rick :

You can post a pic here from a PC or Mac (not a phone or tablet)by clicking on the paper clip icon in the tool bar at the top of this dialogue box

Rick :

If you're sure this device is not on the bldg water main then we can try to tweak it

Rick :

The downside is that it could be plugged with rust and nothing you do will matter or it could fail and keep pushing the pressure up when you want it to stop. If the latter you can always close the shut off valve that should be on the same line

Customer:

I see. I also know how to release pressure from the boiler if necessary (there's a tube leading out of the boiler that has a release). Trying to post a pic now

Customer:

Thanks for your patience. Terrible Internet connection down here in the basement with the boiler...

Rick :

You shouldn't mess with releasing pressure via the relief valve (what you seem to be describing)

Rick :

The relief valve may not seat properly and could continue to leak after you release the lever

Rick :

You can drop the pressure by opening any hose bibb (faucet) on the system.

Customer:

Full Size Image

Rick :

that's it

Customer:

Here's the back of the expansion tank and the pipes leading into it

Rick :

It looks like a good one and fairly new at that

Customer:

Replaced two years ago I think

Rick :

Odd that it won't keep the pressure up

Customer:

So I should open the bolt on top of the bell?

Rick :

You want to crank the screw down to boost the pressure

Rick :

backing the screw off lowers the pressure

Customer:

Ah, of course. Ok, I'm grabbing my wrench now and will tighten the bolt...

Rick :

you'll probably have to back off the nut at the base of the adjustment bolt first

Rick :

be sure all the shut off valves on that feed line are open or this won't do any good

Customer: Ok, trying now... Do I try to tighten completely or just 5-6 rotations?
Rick :

Turn it until you hear water runnig. I'd only do 1 turn at a time then see what happens

Customer: Ok, the two valves you see in the upper left of the pic are open (fully counter clockwise)
Rick :

The position of the bolt determines the pressure, you don't want to crank it in too far

Rick :

Be aware that boiler gauges are often not accurate.

Customer: Ah, is there another way to assess if the pressure is building? This gauge seemed
Customer: to register at least the changes in pressure last year
Rick :

Only with a test gauge which you screw onto a hose bibb at the boiler. You can get them at any plumbing supply house and maybe even the big box stores. Best to get a gauge with 100 as the max range

Customer:

Gotcha. There's a hardware store a block away if I need to make a run.

Customer:

So the boiler is still warm, but not super hot like yesterday. I have the heat turned up all the way from the controller inside the apartment.

Rick :

Well first you need to get the water up to your apartment level

Customer:

Is there anything I should do to the boiler itself? Or the circulator?

Rick :

Not to boost the water pressure

Rick :

If the boiler/burner doesn't respond to a call for heat from the thermostat then that's a different problem

Customer:

I'm upstairs uploading some pics for our reference and then heading back down to the basement...

Rick :

OK

Customer:

Full Size Image

Customer:

Here's the SlantFin boiler

Rick :

Hold off on more pics for now

Customer:

Full Size Image

Customer:

Oh, sorry. This is the valve in the apartment, which I have open. Should I tighten the valves on all the radiators before heading back down to the basement?

Rick :

No need. First thing you need to do is get the water up there.

Rick :

Turn up the thermostat before you head for the basment

Rick :

If we need to do any more trouble shooting you'll probably need a multi meter

Customer:

Great. Thermostat is turned up. Heading back down now...

Rick :

ok

Customer: Boiler is hot. No change in pressure (according to this gauge)
Rick :

Put a couple more turns on the screw. If you can't get the pressure up it won't matter if the boiler works or not

Rick :

You did say there was no water coming out of the bleeders on your radiators?

Customer: I've screwed the bolt on the bell all the way in now
Rick :

You should have water rushing into the boiler with the screw all the way in

Rick :

pressure should be climbing fast

Rick :

Don't leave it like that and walk away unless you turn the valve in the line before it off

Rick :

If you aren't getting anything flow then either the valve is clogged up or there is a problem with the water supply

Customer: The valve on the pipe leading to the boiler (and connected to the bell and expansion tank) is fully open (counterclockwise)
Rick :

I got that before. If your pressure isn't rising quickly then either the feeder is clogged or there is a problem with the water supply

Rick :

You might want to take a run to the hardware store and get a test gauge to verify the pressure on the system

Rick :

are you still with me?

Customer: Yes. Looks like I'll need onsite help then? Are you based in the New York City area by any chance?
Rick :

I'm in NH, sorry I don't know anybody in NYC

Rick :

Don't leave the screw on the feeder cranked all the way in. back it out to ~ where it was before

Customer:

Roger. I just loosed the screw on top of the feeder.

Rick :

and shut off the valve on that feed line just in case

Customer:

Hmm, anything else I should try before calling someone onsite?

Customer:

Ok, shutting off that valve now, too.

Rick :

We've tried everything to bump up the pressure short of pulling the plumbing apart. So there isn't much left you can do. You could try a test gauge on the system but if you don't have the water up to your radiators checking the pressure is a waste of time

Customer:

Understood. Thanks, XXXXX XXXXX really appreciate your time and assistance.

Rick :

You're welcome!

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