Help! Hot water boiler problem.

Paul Holland_2

was the boiler the only thing that was replaced? I usually like to see all the parts get changed with the boiler. New circulator, flow checks, expansion tank. The whole 9 yards.

2 faulty relief valves should be uncommon. I have seen autofeeds fail and not let enough pressure into a boiler which caused the loops to get airbound. I have not heard of a fast fill letting in too much water.

Where is the water feed connected to the boiler? If it is to the suction side of the circulator, guarenteed that is your problem. The pressure at the suction side of the circulator is quite a bit less when it is running compared to when the system is not running. The fast fill is satisfied until the system kicks on. It then senses a reduced pressure and it thinks it needs to add more water.

Keith McWherter

Hot water boiler problem

First, let me assure you that I am a rookie when it comes to hydronics. The situation is as follows. My parents had a Dunkirk gas boiler installed by a local gentleman a few years ago in their two story home. Currently, the boiler is releasing water out of the presure relief valve at the rear of the boiler at a rate of 5 gallons per 24 hour period. We replaced the original presure relief valve, thinking that may be the problem. It did not help. Also found info on boiler web-sites describing this intermittent problem and checked the steel expansion tank for excess water. The tank was almost empty. It also suggested reducing the pressure. Dad has played with the pressure reducing valve in the main water feed pipe with little change. The installing gentleman has been to the house and says he did not know what the problem was and left.

Two questions. One, is the pressure adjusted using the pressure reducing valve and if so, how do know when the setting is correct? Two, if that is what reduces the pressure and it has not helped so far, what else should we be loooking at? Would apprceciate any advice that is available. Thanks, Keith

Rob T

First off I am

not a pro but a homeowner also. Maybe I can be of help anyway.:)

It sounds like excess pressure is the problem. Your parents system should be running at about 12# pressure when cold and in the 20# range when hot.

It may be that the PRV is leaking through allowing the pressure to build. If there is a shut-off at the PRV I'd adjust the pressure to 12# cold and then shut it off and see if the pressure stabilizes. If there isn't a shut-off one should be installed.

Sounds like the expansion tank is the older steel type, if so replacing it with a bladder style is a good idea. (But not necessary, mine worked fine for 40yrs. I mainly replaced it because I kept hitting my head on the Air-Trol.)

Unknown

How did you determine the tank was empty?

Hopefully, not by how much comes out when you open the drain valve......

You also need to put air INTO the tank, as you drain water out.

Noel

Keith McWherter

Noel,

I connected a hose to expansion tank and drained what little water was in it into a five gallon bucket and got about two inches of water.

Unknown

It will stop draining because ther is a vacuum in the tank,

> Noel,

>

> I connected a hose to expansion tank and

> drained what little water was in it into a five

> gallon bucket and got about two inches of water.

Unknown

It will stop draining because there is a vacuum in the tank,

and until you break the vacuum, it will STAY full of water.

Picture this.... fill a glass bottle with water. Fill a pan with water. Turn the bottle over and stick the open end into the water in the pan.

Wait until the water comes out and the bottle is full of air.

Your tank won't drain through a hose that has it's end in a bucket. I doubt it will drain with a hose on the valve, at all. Air can't get in.

Noel

Aidan

Sounds like...

It sounds like an excess pressure problem to me, too.
Is there a pressure gauge? Does it return to 0 with no pressure applied? What does it read with the system cold & hot?

Keith McWherter

Thanks Noel, simple physics. Sometimes the brain has a freeze every now and then. I'll check again.

Keith McWherter

Thanks for replying Rob. The starting pressure is around 10 pounds and I have seen it reach around 25 pounds when running, but nothing higher has been evidenced. I'll check the PRV and possible shut-off valve. I don't remember seeing a shut-off valve, good idea to have one like you said. Thanks again.