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Relief Valve Dripping Mornings

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Brunton
Brunton Member Posts: 9
I have a Weil-McLain Ultra heating system (155k BTU). It feeds mostly cast iron radiators. System has been in place for 2 1/2 years.
System WAS baseboard hot water, but we started converting three years ago (too little capacity in baseboard, plus we like evenness of cast iron heat). We have four zones, controlled by zone valves. We've added several cast iron radiators each year - system has not burped once until this year.
Following installation of one cast iron radiator this fall, boiler relief valve drips about a quart of water each morning when the entire water volume is heated (all zones open at that time) as the system brings house to daytime temperature levels.
I suspect water volume in system is now at the point that expansion tank is too small. System is still under warranty - installer knew of plans to convert entire house to radiators (22 when finished; 17 in now. Two BIG ones, several small ones to go) when system installed. They installed a size 30 expansion tank. Replaced earlier this fall with size 60, and problem reduced but not eliminated.
Installer is now spending hours repiping the boiler system, moving the boiler circulator from the return side to the supply side of the boiler to eliminate head pressure at relief valve. I'm sceptical of this - I think it will mess up our entire system.
I believe the next size up tank will solve, or significantly reduce, our water leakage issues.
Questions - 1. I have a radiator heat sizing guide; anyone know of a complementary water volume guide (to determine total volume of water in system, thus able to calculate delta volume and determine proper expansion tank size)? and
2. Am I completely off the mark thinking this is a simple water expansion issue?

Thanks, and sorry for the long post!

Mark B.

Comments

  • Norm Harvey
    Norm Harvey Member Posts: 684
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    Moving the circ to the supply side is great!... if there are other changes to make it a proper "pumping away" system

    As far as the water volume calc, I use Siggys software, but I think Amtrol has an expansion tank sizer on their website.

    As far as the water dripping issue, it can come from a few places

    1) Improper sized or ruptured expansion tank
    2) Excessive water temperature in the boiler
    3) A water feed valve leaking
    4) A leak in a DHW tankless coil or indirect DHW tank
    5) Bad seat in the relief valve itself due to improper valve installation and after one of the previous 4 things has happened.

    Hope that helps



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    There was an error rendering this rich post.



  • > I have a Weil-McLain Ultra heating system (155k

    > BTU). It feeds mostly cast iron radiators. System

    > has been in place for 2 1/2 years. System WAS

    > baseboard hot water, but we started converting

    > three years ago (too little capacity in

    > baseboard, plus we like evenness of cast iron

    > heat). We have four zones, controlled by zone

    > valves. We've added several cast iron radiators

    > each year - system has not burped once until this

    > year. Following installation of one cast iron

    > radiator this fall, boiler relief valve drips

    > about a quart of water each morning when the

    > entire water volume is heated (all zones open at

    > that time) as the system brings house to daytime

    > temperature levels. I suspect water volume in

    > system is now at the point that expansion tank is

    > too small. System is still under warranty -

    > installer knew of plans to convert entire house

    > to radiators (22 when finished; 17 in now. Two

    > BIG ones, several small ones to go) when system

    > installed. They installed a size 30 expansion

    > tank. Replaced earlier this fall with size 60,

    > and problem reduced but not

    > eliminated. Installer is now spending hours

    > repiping the boiler system, moving the boiler

    > circulator from the return side to the supply

    > side of the boiler to eliminate head pressure at

    > relief valve. I'm sceptical of this - I think it

    > will mess up our entire system. I believe the

    > next size up tank will solve, or significantly

    > reduce, our water leakage issues. Questions - 1.

    > I have a radiator heat sizing guide; anyone know

    > of a complementary water volume guide (to

    > determine total volume of water in system, thus

    > able to calculate delta volume and determine

    > proper expansion tank size)? and 2. Am I

    > completely off the mark thinking this is a simple

    > water expansion issue?

    >

    > Thanks, and sorry for

    > the long post!

    >

    > Mark B.



    What is the pressure in the system when it is cold, and what is it when at full temperature and the valve is leaking?


  • What is the pressure in the system when it is cold, and what is it when at full temperature and the valve is leaking?
  • Brunton
    Brunton Member Posts: 9
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    Per boiler pressure gauge: Pressure when cold is about 12 psi; when hot about 21-24 (the valve is dripping; it is a 30 psi valve).
  • Norm Harvey
    Norm Harvey Member Posts: 684
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    There was an error rendering this rich post.

  • ALH_4
    ALH_4 Member Posts: 1,790
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    dripping

    If the relief valve is dripping at 24psi, I would replace the valve. I would also replace the expansion tank because of the wide variation in pressures. It is likely that the bladder has deteriorated and the tank is now water-logged. This is the perfect opportunity to increase the size of the tank. It cannot be too large. Amtrol has sizing information for their expansion tanks on their website.
  • Ragu_5
    Ragu_5 Member Posts: 315
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    Mark...

    Have your licensed guy install a larger expansion tank; the more expansion, the merrier (sp). Jack.


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  • Brunton
    Brunton Member Posts: 9
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    > Have your licensed guy install a larger expansion

    > tank; the more expansion, the merrier (sp).

    > Jack.

    >

    > _A

    > HREF="http://www.heatinghelp.com/getListed.cfm?id=

    > 428&Step=30"_To Learn More About This

    > Professional, Click Here to Visit Their Ad in

    > "Find A Professional"_/A_



    Thanks for all the suggestions, guys.
    The relief valve has been changed - twice.
    Installers were at the house all day, moving the boiler circulator from the return side to the supply side (this is a primary / secondary loop system). Turns out the boiler pressure gauge reads about 10 psi low for some reason.

    I've been telling these guys for weeks that a bigger expansion tank will solve this entire problem. They went from a 30 to a 60, but rather than spend a couple hundred bucks putting an even larger one in, they opted to spend now at least 20 manhours messing with things. This system has 17 generally good-sized cast iron radiators, so there is a big water mass - lots of expansion as it all heats up. The two guys out here today (one the installation supervisor!) do not even understand what the expansion tank really is for! They jacked the pressure in the tank to about 20 psi (might not be that far off, as this is a three-storey house).
  • Brunton
    Brunton Member Posts: 9
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    Thanks for all the suggestions, guys.
    The relief valve has been changed - twice.
    Installers were at the house all day, moving the boiler circulator from the return side to the supply side (this is a primary / secondary loop system). Turns out the boiler pressure gauge reads about 10 psi low for some reason.

    I've been telling these guys for weeks that a bigger expansion tank will solve this entire problem. They went from a 30 to a 60, but rather than spend a couple hundred bucks putting an even larger one in, they opted to spend now at least 20 manhours messing with things. This system has 17 generally good-sized cast iron radiators, so there is a big water mass - lots of expansion as it all heats up. The two guys out here today (one the installation supervisor!) do not even understand what the expansion tank really is for! They jacked the pressure in the tank to about 20 psi (might not be that far off, as this is a three-storey house).

    Well, anyway, I bet the supervisor a six pack that we would find a container full of water underneath the relief valve pipe in the morning.
  • MikeL_2
    MikeL_2 Member Posts: 494
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    One more thing to check. If you have an automatic makeup valve from the city water supply, make sure its pressure is set to the lowest expected value in your system. Otherwise it will charge the system to a higher pressure, and then when the boiler heats up the relieve valve vents as the expansion tank won't be enough.
  • Anna Conda
    Anna Conda Member Posts: 122
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    You seem to be under the impression that changing the system to "pumping away" is a waste of time and money. This is untrue. By doing this, they're probably solving problems you didn't even realise you had, and are certainly preventing future problems from occuring. They are correcting an error they found with the initial install - that's never a waste of time.
  • Lurkin' Murkin'
    Lurkin' Murkin' Member Posts: 136
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    If the instructions show the boiler loop pump on the return, you can't say it was the installer's error. Where the cold water feed is located, in relation to the nearest pump and expansion tank, is critical to how the system pressure will be maintained. If the pressure gage is tied into the supply water piping, then it will read quite a bit lower than the highest system pressure, when the pump on the return piping is running (due to the pressure drop through the heat exchanger).
  • Brunton
    Brunton Member Posts: 9
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    I don't think I DID say that installing the pump on the return side was an error. I DO think moving it was a waste of time. I thought so yesterday when they were doing it, and then again this morning when my wife found water from the relief valve in the container we put under the outlet pipe again. Guess I win the six-pack.

    Anna Conda, what unknown problems did I likely have? And what future problems is moving the primary loop circulator to the side opposite of the manufacturer's recommendation avoiding?

    I talked to an engineer at Weil-McLain today. He indicated that it didn't really matter which side the pump was on, as long as the boiler still had sufficient water flow. He also confirmed that the problem is a too-small expansion tank. That size system (155000 BTU) with cast iron radiators requires a model 90 tank (it's right there in Amtrol's specs - on the web - and those are same specs Weil-McLain uses). The installers opted to put a model 60 in place of the original model 30, which has the same water acceptance limit (2.5 gallons) as the 30 (having a larger air pocket, the 60 doesn't let the pressure spike so much as it fills).

    So we'll see what the installer decides to do next.
  • Gus_4
    Gus_4 Member Posts: 1
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    Relocation of the pump to the supply line was a good suggestion. Perhap, increasing the expansion tank size a better idea. But, (always a but) it appears the problem only happens in the AM when all zones are calling. Perhaps installing a a boiler bypass and controlling the temperature differential will help eliminate the problem. A proper check valve and a gate valve for adjustments along with temperature gauges. It appears after all said and done that maybe when all zones are calling the unit runs extra long, expanding pressure (above 30lb on your system)till the point the relief valve reliefs. If the bypass cycles the boiler on and off the pressure in the system will be controlled better. Just a suggestion.
This discussion has been closed.