Amtrol WH-7L causing boiler pressure to go up + leaking

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Old 04-05-20, 08:00 AM
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Question Amtrol WH-7L causing boiler pressure to go up + leaking

Hi Folks, we have an Amtrol WH-7L and there is a small leak coming off drain/purge valve at the bottom of the tank (between the boiler hot in and boiler return valves). If the cold water supply is turned on, the pressure on the Weil-McLain boiler system goes from normal operating pressure (+/- 15psi) to approx 40psi, but as soon as the cws is turned off this drops back to normal (+/- 15psi). We have just replaced a ton of parts on the boiler itself (Pump, Pressure relief valve, drain valve) and the baseboard heating is working great.
The cws is direct off the house system (well water - runs +/- 40psi) with no expansion tank or pressure reducing valve.
I am wondering if somehow the heating core has fractured in some way and as soon as we open the cws it's pressuring the heating loop ? Any ideas ?
 
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Old 04-05-20, 08:11 AM
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hi Dune

The guys who know Im sure will be around, but I think you are supposed to have a pressure reducing valve (PRV) after the cws. That reduces the house pressure (40+ in your case) down to the proper pressure for a cold boiler (something like 12 or something like that). If you do have a PRV maybe its bad.

The knowledgeable guys will be along Im sure.


 
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Old 04-05-20, 08:29 AM
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Thanks for that - and no PRV between the Hot water maker and the cws - the boiler has a PRV (set to 12Psi) and that's brand new - so the boiler side is working great - just the hot water maker side is now causing the pressure issue (pressure goes up) as soon as I open up the cws to the hot water maker.
 
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Old 04-05-20, 09:11 AM
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OH I see what you are saying and that is in fact what you wrote in the first post my bad! They will be along Im sure. Good luck!
 
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Old 04-05-20, 10:43 AM
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D,
When you shut the domestic cold water off to the HWT is it still open to the boiler. The tank and boiler should have individual shutoffs. If this is the case and the cold water feed does not effect the boiler when you shut the tank feed off it sounds like you have a hole in your tank coil. The boiler pressure in the coil is 12 psi and your house pressure being 40 psi, will overtake the coil pressure and leak into the boiler. No pressure reducer is needed on this tank.

Hope this helps a little.
 
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Old 04-05-20, 10:51 AM
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Thanks Spott - yes - separate cold water feeds for both the HWT and the Boiler - I suspected there was an issue with the boiler coil in the HWT and that the 40psi house supply was pushing back into the boiler loop. We are debating whether to replace the HWT with the same or go tankless - we have gas piped into the utility room and install of either is straight forward.

And I'm the 3rd owner of the house - might be worth a try to see if it is under warranty !

thank you
 
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Old 04-05-20, 11:24 AM
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You should have isolation valves on the boiler supply and return from the boiler to the tank. To further verify if the coil is the problem, shut the supply and return valves off and open up the cwf to the tank. If the problem is the coil, with the valves to the boiler off the boiler pressure should not change.

I believe the warranty is only to the original purchaser but it never hurts to check.
 
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Old 04-05-20, 11:33 AM
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Yep - confirmed - coil is shot - locked the boiler supply and return off and no pressure change when opening the cwf to the hot water maker ! A new coil looks like it's almost the same price as a new hot water maker !
 
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Old 04-05-20, 11:57 AM
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D,
Found this depending what you have.

https://www.hvacbrain.com/amtrol/hot...acement-parts/
 
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