Boiler system over-pressuring

Ken Caverly_2

The indirect HWT was not heating. It appeared the taco 007 circulator was not working. Plumber installed new 007, now it still refuses to heat. If the thermostat on the HWT is disconnected for a few hours, and then reconnected, it appears the circulator begins to circulate. Called plumber for advice and he suggests an air lock in the 007 probably prevents flow and that this air lock should work its way out.

Pressure in the system usually hangs around 20 psi. After the plumber left yesterday, it was running at 12 psi, which the plumber said was a very good level. Now, it is running at 35. The boiler release valve says it is set for 30 psi. It has not blown yet, but I shut the system down until I can get some answers. However, it is currently -22 C, and it's Friday p.m., and the plumber doesn't know when he can get here.

He did suggest that once the system was shut down for the 007 change, that the pressure fill regulator may have started to act up. He will probably start by replacing that unit.

Does anyone have any suggestions? I don't want to have this turn into a trial and error by a plumber that isn't familiar enough. However, it is the company which advertises their radiant expertise and seems to be more knowledgeable than many of the others in this town.

Help!

Thanks,
Ken

Brad White

The range of pressure fluctuation

from 12 to 35 tells me to look at a few things:

1) Undersized expansion tank (does the pressure rise and fall with temperature? If so, this leads me to this item).

2) Leak-by at fill valve. If you isolate the cold water fill valve does the rise in pressure stop?

I assume there is no immersion coil for DHW such that might leak domestic water into the boiler to cause a rise in pressure.

That the relief valve has not blown concerns me most of all. These will usually weep as the pressure gets within a pound of release (a function of the gauges accuracy I suspect). Holding 5 PSIG above the release point means, who knows what the release point is?

12 PSIG is fine for a two story house. So is 20 so long as the pressure holds and does not approach the release point of the relief valve. 20 PSIG helps keep any air bubble smaller, 60% the size they would be at 12 PSIG.

Again, check the pressure as the boiler heats and cools. Then find the expansion tank. While you are at it, make sure the 007 is pumping away from it.

Ken Caverly_2

Thanks Brad.

The plumber did come by again. It turned out that the capacitor on the 007 unit was shot and that he had only changed the cartridge last trip. That is why it only worked after it had been disconnected for awhile to allow the capacitor to reset. A new complete 007 has been installed and the water heater is back in action.

As for the pressure build-up, he shut the filler tap off at about 20 lbs and said to watch the pressure gauge. If it climbs as the system heats up I should let off some pressure thru the boiler relief valve. If it is still fine after it heats up, then reopen the filler tap and see if the system pressure reducer holds the pressure or allows it to creep up.

At least we have heat and hot water to get us thru. If it needs more work it can be fit into the plumbers schedule next week.

He didn't have the same attitude of concern about the reset not blowing as you did. Do you think a new reset valve would be a wise and safe investment.

Brad White

New Pressure Relief Valve

If your current pressure relief valve did not relieve at 35 PSIG at the factory, it would not ship. It failed. You know that it has in the field by that fact alone.

Yes, I would replace it.

I cannot imagine the circulator issue being related to the pressure issue, not for a rise from 12 to 35 lbs. Watch the gauge as she heats up and let me know what you see.

Glad your plumber made a return trip! Where are you that you get in the -20's?