We had a new Burnham V83 boiler installed about 2 years ago. Ever since it was installed, it has been dripping water (mostly hot, but cold, as of today) out the back of the house via the overflow tube.

We have had the pressure relief valve replaced repeatedly, but it only solves the problem (if at all) for a short time. Why does the valve keep blowing?

We have two Amtrol Therm-X-trol ST-5 expansion boxes on the system. Are they sufficient? They are installed on two different parts of the piping.

We also have a heat exchanger (since the in-floor tubing installed is entran II, which is oxygen permeable, and the 12-year-old boiler had rusted out, hence the replacement).

The boiler heats our in-floor system, and also provides the heat to heat the hot water tank, so we run it year-round.

According to our oil company, our oil consumption INCREASED significantly since we had the new high-efficiency boiler installed. (Maybe because we're dumping up to 1 gallon of hot water out the back of the house every hour?)

Any suggestions as to what might be the problem would be appreciated. The installers certainly can't figure it out!

 

Leakage from the safety valve is almost always caused by one or more of three things: Leaking make-up water (auto fill) pressure reducing valve, defective or inadequate expansion tank or a domestic water heating coil.

If you can take several pictures of the boiler and the piping to it (more pictures are always better) then someone can get a better idea of how to guide you to the problem.

To post pictures you need to first upload the pictures to a photo hosting site such as photobucket.com or villagephotos.com. and then post the public URLs for the pictures (or album) here. More pictures are always better than fewer. Please have CLEAR pictures and have both close up pictures and ones from a far enough distance that we can see how the various parts are interconnected

 

Thermal expansion tanks are made for domestic hot water systems and come pre-charged at 40psi. They can be used for the heating system if the charge is lowered to 12psi. Has anyone checked this? Also wiould have to ask why you have 2 located in different parts of the system? Is there one on each side of the heat exchanger? If so it's also possible the tank is too small.

 

Here are some photos of the system.

Overall System:

The boiler (front and center) heats water going up and to the right, past the expansion tank (top center, white tank) then past the pump (red object, top right) to the heat exchanger (rectangular object, just below pump). This is the "boiler side" of the heat exchanger: water temp should be between 160 and 180 (according to my maintenance guy) and pressure is between 15 and 20 psi (as read from the boiler gauge.) The water heater is on the left and is heated by "boiler side" water. Above the water heater you can see the red pump which draws water from a pipe running across the back (behind all the feeds to the radiant floor tubes) and over to the right of the heat exchanger. The return is the lower pipe running across the back.

On the "floor side" of the heat exchanger is another expansion tank (just to the left of the heat exchanger). The "floor side" runs from the heat exchanger, through a variable mixing valve (blue box in center below flue) to the separate zone pumps (three red pumps in a row, below and left of mixing valve.) This pushes the water to the in-floor radiant heat tubes (Entran-II) But I don't think the floor side is involved. (I could be wrong.)

The overflow tube has three inputs: 1) The boiler pressure relief valve (see on top of the boiler with the green tag and running straight back) 2) The back flow valve (hidden behind the boiler flue, and to the left of the green pressure reducing/auto fill valve) and 3) The pressure relief valve from the water heater (seen above the water heater, right-most tube sticking up, partially obscured by the plastic tray.)

We know that the back flow valve is not (likely) the problem because A) the drip tray and tube is dry, B) it is new and C) the back flow guy is the one guy I think really knows his stuff.

The boiler pressure relief valve is currently what my oil company maintenance guy believes is the problem. He believes it may be a "victim" of high pressure in the boiler. He also suspects the Amtrol Therm-X-Trol XT-5 is too small. But I did get him to test the pressure in the unit and it tested at 12 PSI (with 160 degree water in boiler.) He estimates about 8-10 gallons of water in the "boiler side" loop.

Below is a picture of the auto fill / pressure reducing valve:

The back flow prevention valve is one year old. The back flow guy is scheduled for the annual inspection on Monday. The installer guy says the auto fill / pressure reducing valve is probably set for about 12 psi and recommended we lower it to either 10 or 8 psi. He figures it will reduce the overall system pressure. He, however, seems to be motivated to tell us "whatever will make us go away", and I am to the point of doing exactly the opposite of what ever he says.

The problem history is that the new boiler always "leaked" water out the overflow. It was installed in August of 2006. It took us about 9 months after the installation to convince the installer that the leaking was a problem. Eventually, the old back flow was replaced in June of 2007. At the same time the boiler pressure relief valve was replaced. The leak stopped for about 1 or 2 months. The oil supply company did a routine maintenance in May and the leak got worse. We now have the lead technician from the oil supply company working on it. The installer is involved again because, well, they "asked for it". We were more or less happy to not talk to them again except they billed us for an "outstanding bill" for services from the June 2007 work. We are now holding their feet to the fire (boiler?) to try to get them to own up to the problem and get the whole thing working. But we have a real trust problem with their guys.

As was mentioned in the first post, the water coming out now is cold, ambient temperature. Which is puzzling because the water dripping in May was warm water.

Anyway, I didn't mean this reply to be a shaggy-dog story but this has been a long standing problem and very frustrating.

-MpH

 

Links/pictures are not showing. Looks like photobucket is down or got jacked.

 

Can you post more pictures from some different angles so I can see the piping from different angles and also the piping behind the boiler?

Does the system on the "floor" side of the heat exchanger have its own pressure reducing make-up water valve and also a safety valve? Does it have its own pressure gauge and thermometer?

What are the actual observed pressures and temperatures on the boiler-mounted gauge when the boiler has not run for some time and when the boiler has just stopped running?

 

Hello,
I think I might know what your problem is.

ST-5 expansion tanks are designed for domestic hot water not hydronic heat and are pre-set to 40 psi which is way too much for a heating system. It is just like not even having a tank. From your pics it looks like both the exp. tanks are both connected on the heat side. You should actually use one of them for the domestic side of the water heater.

And as far as sizing is concerned, use the charts in this brochure to determine the correct size and model # of tanks/s.

http://www.amtrol.com/pdf/extrolbrochure.pdf

 

I just reread the entire post and as furd has mentioned earlier, we need temps, and pressure readings.

When the relief valve is dripping, can you tell? That way you could tell which line is the culprit.

Do you have a backflow device on your house water system?
Do you have an expansion tank on the hot water heater, domestic side?

Feel the relief tubes and see if one is a little warmer than the others.

If the pressure gauge is reading 30 psi constantly we are looking in the wrong direction.

Can you take more pics? Possible piping problem.

Could we have an over temp situation? Need readings.

IMPORTANT:
Readings should be when boiler is cold and when boiler is up to temp. Both pressure and temperature.

I definitely think the tanks are undersized and I would double check the pressures of both tanks when the pressure is relieved from the heating system.

If there are some check valves that are improperly placed you may have isolated the boiler from the expansion tanks.

I gave you a link to Amtrol tank sizing. Check it out.


ps - sorry heatpro, I did not see you already had mentioned about the ST-5 tanks as being domestic.

 

Mark said:

and I want to expand on this just a bit.

You can not check the pressure of the air charge in the expansion tank when there is any pressure on the water side. You will not get a meaningful reading. One MUST relieve the pressure on the water side before attempting to measure or adjust the air charge in the tank.

 

And I'll expand on what the Trooper posted...

If these expansion tanks were installed with a 40 psi precharge then you CAN check the pressure with the heating system in operation. The pressure will be higher than the boiler gauge reads. If this is what you find then let air out of the tank until the pressure matches the boiler pressure. This will NOT guarantee that the pressure is correct for the system but it WILL make sure that the pressure is not too high for the system.

If you can allow the boiler to come to room temperature then check the boiler pressure and if it is somewhere between 1o and 15 psi you can release the air pressure in the expansion tank until it is just slightly higher than the boiler pressure.