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Phil
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 5648
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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Domestic hotwater is the priority zone but does not maintain

Customer Question

Domestic hotwater is the priority zone but does not maintain the hotwater temp when heating goes down at night or is not called for. Takes several cycles of running hotwater to raise temperature. Weil McClain Gold plus 30 tank. Aguastat has been replaced & drywell is good.
Submitted: 9 months ago.
Category: HVAC
Expert:  Daniel Plourde replied 9 months ago.

Hi I am dan I can help you with this. The priority means that if the tank zone calls for heat then it will turn off the heating zones until the tank is satisfied. Are you having problems with the domestic water heating up or the boiler water?

Customer: replied 9 months ago.
Domestic hotwater temp is not maintained when heating is not called, overnight or when zones are not calling for heat. Takes several cycles of running domestic hot water to raise temp. New aquastat on W.M Gold plus30 has been installed.
Customer: replied 9 months ago.
System was fine until a few months ago.
Customer: replied 9 months ago.
Circulator s are fine
Expert:  Daniel Plourde replied 9 months ago.

When the heat is calling is the temp fine? Is it just a problem when the heat is off? How old is the tank?

Customer: replied 9 months ago.
Sorry for the delay we lost our internet connection. Temperature is fine when one of the other zones are calling for heat. The tank is about ten years old. Drywell is fine, no moisture and thermostat was just replaced. Priority switch is on.
Expert:  Daniel Plourde replied 9 months ago.

ok was the aquastat changed after the problem or did the problem start after the aquastat was replaced. Also what is the model number of the aquastat.

Customer: replied 9 months ago.
Was changed after the problem but did not fix the problem.
Expert:  Daniel Plourde replied 9 months ago.

ok what is the model of the aquastat and the zone pannel?

Customer: replied 9 months ago.
Zone panel is aTaco E20B the boiler aguastat is a Honeywell dual aquastat type L4081B, the thermostat on the hot water tank is is a T100 30°C 70°C
Expert:  Daniel Plourde replied 9 months ago.

ok the next thing i would look at is the zone panel. first thing i would try is switching the tank wires to one of the other zones and see if that helps the problem or if you get a problem with the zone you switch to the priority zone

Customer: replied 9 months ago.
That is going to take some time. Does it matter how fast I get back to you?
Expert:  Daniel Plourde replied 9 months ago.

no i relize it will take some time to test that out. just reply back when you can. what we are testing is the zone board may be bad or maybey intermitent where is does not always bring the boiler on when the water heater calls but turns on the circulator

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