System 2000 water pressure problems (too low to too high)

71camaro

Hi all:

Somewhat new to boilers/HVAC systems and seeking some help here. I apologize for the long post but want to hit as many points as possible to reduce confusion/possibilities on this.

Have an older Energy Kinetics System 2000 boiler located in a basement that serves for both home heating and for domestic water. The system has a Carlin EZ Gas Pro Conversion Burner installed. Home heating is old-style cast iron radiators on two floors in the original portion of the home (single zone on boiler), and baseboard units split between the first floor and second floor of an addition (two separate zones, one per floor). In total, there are three heating zones in addition to the domestic hot water loop.

A few weeks (months?) back, started getting somewhat steady discharge from the pressure relief valve on the boiler. Several service techs were supposed to come out, none did, so I've decided to perform repairs on my own.

All the providers stated on the phone they felt it was either a bad expansion tank (ruptured bladder), or one that needed servicing. I ordered a tank, and also a new pressure relief valve because it appeared that the valve was not seating and was leaking even when the system had cooled.

The boiler has a 30 PSI max pressure, so an Apollo Valves 30 PSI pressure relief was ordered. The expansion tank was charged to 15 PSI in consideration of the baseboard/radiators on the second floor. The expansion tank is isolated by a ball valve. The valve was closed/tank replaced, and the valve reopened.

The boiler fill was then closed, the pressure relief valve replaced, and the fill then reopened (the fill seems to have been kept open and never closed at any point other than servicing of the system). All work was performed with the system cold/having not run all day. Upon opening the fill, the system pressurized to a gauge-indicated 35 PSI.

I then turned my attention to the feed-water pressure regulator. I attempted to adjust the pressure back on the regulator (tag indicated that it was set factory 12-15, and had a 10-25 range). No adjustments seem to make a difference and it flows over 30 PSI regardless of changes to the regulator. I have ordered a replacement and await its arrival, but I now believe that explains my regular water flow out of the pressure relief valve- rather than having a failure of the pressure relief valve, I believe the feed-water pressure regulator had failed and was allowing flow into the boiler at municipal system pressure.

In the meantime, I cracked the boiler fill open and filled the system to roughly 15 PSI to match my expansion tank pressure. Here are where my current issues exist.

With pressure in the system and the feed valve closed, once running the boiler, the pressure still runs up over 30 PSI and begins to bleed through the pressure relief valve. Upon closing and cooling, the pressure shows below less than 10 PSI. After a period, the system pressure will show 0 PSI by the gauge. If the system then runs again, pressure will quickly jump above 10 PSI when the circulator powers up, and will then end up running back to 25-30 PSI as it heats. While it does not then discharge so significantly, the pressure relief valve still tends to exhibit anywhere from a drip to a minimal but steady flow once the boiler and water get to temp. The boiler also seems to short-cycle as it reaches the peak temps/pressure.

Finally, during the lower water pressure instances, the boiler makes a sound most reminiscent of a helicopter, but the sound is much more pronounced above the boiler on the 1st floor (near where the chimney runs up the wall). The boiler's additional sounds are not as noticeable or pronounced when standing beside it. The sound tends to be reduced as the system runs.

As some additional info, one of our home radiators exhibited a leak between sections. Since we're not running heat right now, that loop/zone has been isolated out of the system by closing existing ball-valves while trying to diagnose these pressure issues.

Many thanks for any help that may proceed.

Jamie Hall

If the system is closed off from the water supply, and the pressure behaves as you have described (rising much too high hot, and dropping to zero or near zero cold), then the expansion tank simply isn't doing its job. Since you have a new tank before replacing it again disconnect it from the system. Physically. Make sure there is no water in it and there are no closed valves or anything at all on the water side. Measure the air pressure in it and set that to 15 psi. Leave it for a couple of hours and recheck. If it's still 15 psi the tank is OK. Now reconnect it to the system and make sure all the possible valves between it and the system are open. Adjust the system pressure as needed so that the system pressure also reads 15 psi. See if that helps.

hot_rod

Does it have a plate heat exchanger for DHW? Could be a leak allowing street pressure into the boiler side?

If it has a plate HX is it a double wall? Roger would know.

71camaro

. I wanted to follow up here, performed the above with the expansion tank, and also replaced the fill valve. System now sits at 15 PSI cold and is running nearly flawlessly.

Found that the old fill valve was not regulating the pressure, hence the water flow to the floor, etc.

Now, however, everything is running well, pressure sits at 15 PSI cold, 20-22 PSI hot. No overflow, no pressure drop.

Only issue is this: the boiler is in the basement roughly under the kitchen and dining room. Previously, I believe it could not be heard at all. When we had the pressure issues, it sounded like a helicopter. Now, the vibration sound is much quieter but can be discerned. We had no sound before. Any thoughts on this change?

Jamie Hall

The sound change is most likely some pipe or fitting is touching -- or rigidly fastened to -- some part of the house and wasn't before. It doesn't take much... and can be remarkably hard to find.