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drh 12-17-2007 08:20 PM

How can I increase PSI in my boiler? (pics attached)
4 Attachment(s)

After reading "stonegirl"'s thread on not getting enough heat to her second floor rads, I believe I'm suffering from a similar situation - not enough pressure in my boiler system (my boiler, a Teledyne Laars Modutherm, installed in 1981) is currently sitting at 10psi, and my second story rads do not fill (they bleed air, but no water comes out).

Someone suggested to increase pressure, that a "boiler fill valve" must be opened, but the trouble is, I have no idea which valve I need to turn. So I've provided some pictures in the hopes someone can help me identify the proper valve.

I've attached four pictures - there are settings for High Limit (which as I understand, is water temperature) and another for "Circulator", which I'm not quite sure what its purpose is.

I'm guessing the "fill valve" is the nozzle next to the temperature/pressure gauge in boiler2.jpg, but I could be wrong.

Can someone help shed some light here?

Much appreciated,

ps - I'm a little concerned over the age of this boiler, and I'm looking into potentially replacing it come spring. How long would a boiler of this nature typically live?

redline 12-18-2007 05:25 AM

Need a photo of where the 1/2 copper water lines comes into the boiler.

drh 12-18-2007 08:41 AM

2 Attachment(s)

Originally Posted by redline (Post 81474)
Need a photo of where the 1/2 copper water lines comes into the boiler.

I believe I may have solved this! Where the cold water comes into the boiler unit, I noticed a "backflow preventer" unit which has a small lever on the top of the unit which, when flipped, sounded as though it began allowing *more* water to flow into the unit. Almost immediately (within 10 mins, I noticed the PSI levels begin to increase).

As you can see by the gauge picture below, my new PSI is now in the 25 range -- and after bleeding the rads upstairs, are running incredibly warm, resulting in a very happy owner, and even happier girlfriend.

My question is now, running at 25PSI, am I risking damage to the unit? Or is 25 perfectly normal for a two story dwelling?

Thanks again,

bigMikeB 12-18-2007 05:26 PM

The picture on the left shows the bronze colored pressure reducing valve, not a backflow preventer. I don't like that type of PRV and would change it to a B&G FB38 if it was me, it's much more reliable and has a easily cleanable strainer on the bottom.
25 psi is too high and may cause the relief vavle to blow off when it has run for a while. Drop the pressure back to 12 psi cold or 18-20 hot (@160F).

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