Runnin' Hot and High Pressure

I installed my 520 almost two years ago. I did a total system makeover. I felt like I ironed out most of the bugs being a first time coal owner. BUT, lately its been running hot! This morning up to 260! And the pressure varies from 10 to 35. All zones are working, and I haven't made any changes with the system. The only thing I did change was running a mix of rice and buck from the Harmony mine. Please help! Thanks, Keith.

Welcome to the forum.

The only thing I did change was running a mix of rice and buck from the Harmony mine.

Did you readjust your coal feed and air flow rate? Harmony burns hot, what brand coal were you burning before? What size coal?

The EFM experts should be along shortly to help out.

Water temp up to 260? Do you have a Dump Zone setup? Is all the air out of system?

I've always burned Harmony coal, and I did adjust my feed rate a little. I'm not quite sure what a dump zone is. I referenced the "Pumping Away" book when doing my system. I honestly think my problem might be my expansion tank. I used the old one that was on the previous oil burner. Its about 10 gallons, but I think it might be almost full with water. I do feel that most of the air is out of the system, and again not much has changed. Please try to bail me out of this one! Thanks, Keith

The pressure going high in a water system is usually one
Of. Two things

A bad expansion tank....or one that pressure on the other
Side of the bladder has leaked away...can add air back
If bladder not completely bad

Second is a leaking domestic hot water coil....

The coil was new when I put the furnace in two years ago. How can you tell if its leaking? Also, I don't think my tank has a bladder, its old!

Sounds like two problems to me.

If you have a ceiling hung expansion tank, it could be full of water. Opening the drain valve won't empty the tank unless there is another valve to break the vacuum. If there is no second valve, you can stick a hollow tube up through the valve to the top of the tank to break the vacuum. You can EXPECT a bath, so make sure the water is cold.

Changing coal supply isn't going to cause such a high temperature. You could have a failed high limit on the aquastat, not common, or the limit is just set too high. I wouldn't go any higher than 210 on the high and keep the low around 160 in the winter and 130 in the summer.

Your feed could be too high, but if the high limit is properly set and working, the water temp will never get that high.

Shut off the inlet and outlet of your hot water coil and reduce the pressure of your boiler to 15#. If the pressure stops building overnight, it could be a faulty water supply valve to the boiler, or a pinhole leak in the coil.

Increased pressure with increased heat are usually a sign of an expansion tank issue. Increased pressure without increased heat are usually a sign of a bad coil.

You could have a bad water fill valve, a bad coil, a full expansion tank, or a faulty aquastat.

Thanks stokerman! I'll check those suggestions. One more interesting thing, came home today, temp 180 pressure 9. Very small fire. A few hours later temp 220, pressure 32. Does this help anything? I'll drain the tank an see what happens. Could my water input valve be plumbed in wrong were it fills the expansion tank right away? Is that possible? Thanks for the help.

Sounds alot like an expansion tank problem now.

Stoker-man, thanks for the input. If I wanted to put a bladder type tank in, what size do I need? Also, where is the best place to plumb it in at? Again, I feel my current hook up isn't functional!

If you have a ceiling hung expansion tank, it could be full of water.

This type of expansion tank needs to be drained on a regular basis, at least once at the start of the heating season. There really is nothing wrong with using this type of expansion tank, it just requires regular draining.

Also, the pressure relief valve on the boiler should release at 30 psi. If your pressure has gone above that I would replace the relief valve just to be safe.

Can you post some photos?

Expansion tanks are sized by the number of gallons in your system. Your boiler holds 41 gallons, plus whatever is in your pipes. I think that translates to a #60 Extrol tank, but check their website to be sure. They get plumbed in the supply line, usually near or with the air separator.

You may want to add a ball valve with a drain on the expansion tank side. This way if their is a problem, you could close the pressure to the tank, release the pressure and check the bladder pressure.This would not require draining the whole system and introducing alot of air. Just remember to KEEP the valve OPEN when in service.

Wood'nCoal wrote:

If you have a ceiling hung expansion tank, it could be full of water.

This type of expansion tank needs to be drained on a regular basis, at least once at the start of the heating season. There really is nothing wrong with using this type of expansion tank, it just requires regular draining.

Also, the pressure relief valve on the boiler should release at 30 psi. If your pressure has gone above that I would replace the relief valve just to be safe.

Can you post some photos?

You know its a funny thing I have my EFM 5 20 in 24 years with a ceiling hung expantion tank and have never had to drain it, yet some of my customers furnaces that I serviced I end up draining their water logged expantion tanks every year go figure.

ry

In the house I grew up in we had gas fired hot water heat, we drained the expansion tank every fall and never had a problem. we would shut off the valve to the tank, open the drain valve, then open the air bleed on the shut off valve and let it drain.