Weil Mclain 88 Hot Water Boilers

[YoungApprentice]

I need some opinions on what is what, I have 2 WM 88's in my BR used for Domestic Heat and a 3rd that is used for Domestic HW. Our typical pressure runs between 16-20PSI, closed loop.

The other day PSI shot up to nearly 30PSI (max 50PSI on Boiler), while trouble shooting I found a valve open on the makeup line, clearly adding water to the system and in my opinion raising pressure. I drained the boilers so that pressure went back down to my 16-20 range.

My Project Manager (Mr. KnowItAll, been doing it for 25 years but is only 38, go figure) says that the addition of water or depletion of water has no bearing on pressure. I argued with him but he says it doesn't.

The pressure clearly went up with the addition of water and clearly went down when I drained down the boiler.

Any help will be greatly appreciated.

[prorefco]

Water boilers are usually fed with a pressure reducing valve (pressure regulator) and the pressure is usually set to a few psi above the total system elevation. For instance, let's say the system is 30 feet tall. The feeder needs to pressurize the system to 1 psi for each 2.3 feet of system elevation. Therefore, for a 30 foot tall system, you would need a MINIMUM pressure at the boiler of about 13 psi just to force water to the top of the system. I usually add a few psi so for a 30 foot tall system I would set the feeder at about 16 to 18 PSI with the boiler cold and without the circulator running.

Now, these feeders do wear out over time and often will feed more and more water into the system and over pressurize it. Any little bit of dirt or sediment that might get caught in the seat of the feeder valve can hold it a little bit open.

WHen this happens, it's wise to change the feeder valve and set it up as needed. The shut-off valve to the feeder should always be open.

[ascj]

My Project Manager (Mr. KnowItAll, been doing it for 25 years but is only 38, go figure) says that the addition of water or depletion of water has no bearing on pressure.

I would drain the boiler again and then ask him "why did the pressure go down when I drained it."

I would love to here the answer.

[hpsteamjeff]

It might also be a leaking tube bundle in your domestic hot water heater or heat exchanger. I had 2 Patterson Kelly HWH tube bundles leak after 8 years:patriot:

[JStar]

Did it only go to 30 psi when it was fired up and hot?

[YoungApprentice]

[QUOTE=JStar;6305652]Did it only go to 30 psi when it was fired up and hot?[/QUOTE

Boiler #3 was not running at all. In fact I have the Domestic HW switched over to the LochinVars. Boiler #1 & #2 had been running but were sitting idle at the time I noticed it.

[YoungApprentice]

Water boilers are usually fed with a pressure reducing valve (pressure regulator) and the pressure is usually set to a few psi above the total system elevation. For instance, let's say the system is 30 feet tall. The feeder needs to pressurize the system to 1 psi for each 2.3 feet of system elevation. Therefore, for a 30 foot tall system, you would need a MINIMUM pressure at the boiler of about 13 psi just to force water to the top of the system. I usually add a few psi so for a 30 foot tall system I would set the feeder at about 16 to 18 PSI with the boiler cold and without the circulator running.

Now, these feeders do wear out over time and often will feed more and more water into the system and over pressurize it. Any little bit of dirt or sediment that might get caught in the seat of the feeder valve can hold it a little bit open.

WHen this happens, it's wise to change the feeder valve and set it up as needed. The shut-off valve to the feeder should always be open.

My BR is on the 18th Floor, city water is boosted up to the 18th Floor. My minimal knowledge/learning (I am still in LP Boiler Class) is that gravity works in my favor in this situation. with my demand being below that boilers, not having to be boosted up.

this problem is actually a bit deeper, Boiler #3 is piped as a back-up heat source for domestic heating if needed. Typically it is used as Domestic HW only, but at this time I have it valved off and running on our Lochinvars. The Boiler has filled with water obviously a valve is not holding, but this supports my original question that the water effects the pressure.

I will check on the feeder's tomorrow. It's a new building for me, my last building had 4 little pork chop boilers. Kind of a big jump.

Thanks for the help

[YoungApprentice]

I would drain the boiler again and then ask him "why did the pressure go down when I drained it."

I would love to here the answer.


Knowing him he would write me up for showing him up. :argue:

[flange]

pressure would elevate to whatever was in the line you closed off, or to the relief valve setting, and then open the relief. draining off water will lower the pressure, but if the valve is now closed, you have no protection form water loss right?

[YoungApprentice]

pressure would elevate to whatever was in the line you closed off, or to the relief valve setting, and then open the relief. draining off water will lower the pressure, but if the valve is now closed, you have no protection form water loss right?

Thanks for the reply. There is supposed to be protection from water loss, however after today not seeing any guages on either side of the pressure regulators I am not sure what the hell they have done in this boiler room.

Found a clamped on garden hose used as a crossover for our 4th tier heating lines this morning at 5:40AM when an emergency call came in the "the garage is flooding". got there 20 minutes after recieved call to see garden hose in garage just hanging and water everywhere. Ran up check boiler #2 & #3 and both empty. All I can do is shake my head at some of the stuff I am finding at the new buildings. :nopity:

Needless to say I will be with my helper busy for awhile re-plumbing and figuring out what is what.

Thanks for all the help guys.