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dgr68 02-15-2010 05:32 AM

Boiler Relief Problem
I have a two year old system. Weil McLain Ultra 155, with 4 zones. Been noticing a puddle around the boiler in the moring and identified it was coming out of the relief. Called my HVAC tech and he replaced the valve, ran the system and everything seemed fine. Next day, had the same problem. Tech came back during the next day and couldn't replicate the problem. Said my expansion take seemed ok. Day after that, I woke up early and found the boiler leaking through the relief. Pressure was at 27 psi when it typically runs 17. Seems to be happening during a recovery period in the morning. Any ideas would be welcome. Thanks..

beenthere 02-15-2010 08:57 PM

Could be the autofeed is bleeding water through when it shouldn't.
What type of expansion tank do you have.
A steel tank, or a bladder tank.

Steel tank could be full. Bladder tank could have a bad bladder, or be low on air.
Bladder tanks can't be checked when connected to the system and system presure is pushing against the bladder.

dgr68 02-15-2010 10:19 PM

It's a gray steel tank with bladder inside. First one failed, so this one is less than a year old. Tech tapped the tank and said it was fine because he could hear it was half full of water. Would the expansion tank affect the pressure in the boiler itself? And why would it be intermittent? Thanks for the help.

beenthere 02-15-2010 10:25 PM

Yes, it effects the boiler pressure.

As the water heats up and expands, it needs some place to go. And that place is the expansion tank.
You can't tell if the tank is ok by tapping on it.
Needs to be checked to see if its holding its air charge. And that can't be done while its sensing boiler/system pressure.

Do you have cast iron rads?
What size is your expansion tank? Could be too small. Depending on how many rads you have.

Intermintant. Because after teh relief valve releases some water. The water volume is now low enough that the pressure doesn't get too high.

As your systems water temp drops, so does the water pressure. The auto water feed sensing this low pressure then adds more water to the system. And then when that water heats up. It expands, and the system pressure rises, until the relief valve does its job again.

Relief valves don't go bad and start leaking, unless they are opening too often, or are at their pop pressure for too long of a time. So your other relief valve wasn't bad. Most likely your tank, or auto water feed valve.

Do you have an indirect water heater?

beenthere 02-15-2010 10:55 PM

That other site you posted this question is not a DIY site.
You will get a little help, but not much.

NHMaster 02-16-2010 06:06 AM

Check the tank pressure with system pressure at ) the tank pressure should be 14 lbs.

Close the auto feed to the boiler, drop system pressure to 15 lbs and see if it holds for a few days. If so, change the auto feed valve.

Make sure the high limit aquastat is not set above 200 and that it is fully seated in it's well and reading properly (check it against the gauge)

If you have an indirect water heater it may possibly have a leak in the coil that would be adding pressure to the system but it would happen all the time, not just in the morning.

tk03 02-16-2010 07:18 PM

What is the pressure when the boiler is cooler. The pressure from cold start to 180f should be about 3 - 5 PSI. If the pressure is changing more than that the tank is undersized or lacking air charge.
You were asked what size boiler and what type radiation do you have?

dgr68 02-17-2010 09:19 PM

I have a Weil McLain Ultra 155 condensing boiler driving 4 zones. One zone is radiant Onyx by Watts, one zone is baseboard, two zones have 6 cast iron radiators each. I will try to get a picture of the system tomorrow and take readings. Do not have indirect dhw.

beenthere 02-17-2010 09:39 PM

What is the model number of the expansion tank.

dgr68 02-18-2010 08:07 PM

Expansion tank is Extrol Model 30. Below is a link to pictures:

The first expansion tank went bad about a year into service. This is the second.

beenthere 02-18-2010 08:13 PM

12 rads. Not knowing what size they are. Your a bit small with that #30.

On your second expansion tank in 2 years. Your third one should be a 60.

dgr68 02-20-2010 08:25 AM

1 Attachment(s)
A guy on another site says my PRV and BFP are backwards. I'm assuming that means "pressure reducing valve" and "boiler feed pump"?? Anyone have feedback on how the system is configured? See pic below called "Sys 001" under Additional Options. Thanks..

beenthere 02-20-2010 10:25 AM

BFP is back flow preventer.

dgr68 02-20-2010 02:18 PM

1 Attachment(s)
In that case, he's right. I just read the Watts instruction and they say to install the backflow first. My question would be, is this going to really matter and would it contribute to my pressure spike problem? Should I just pull out the old Extrol and pop in a new 60 and see if that works? If not, what are the chances the Spirovent, backflow, or feed valve are culprits? Here is a close up:

beenthere 02-20-2010 02:35 PM

Neither the Spiro vent nor the back flow preventer can cause it. The pressure reducing valve could.

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