Domestic hot water 150F , set at 110 on thermostat

Old 01-24-23, 04:43 PM
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Domestic hot water 150F , set at 110 on thermostat

Recently had my hydronic heating system with combiboiler repaired/fixed.

The water coming out from faucet and shower is 140-150.

The thermostat next to the boiler tank is set at 110 (before was 130, but I thought that would decrease the temp)

Any fix?

Set at 100

My boiler

Entire system, yes I know the expansion tank should be hung with an air scoop, the tech \"mickey moused " the setup 😞

Is there any easy way to chnage that gauge

Old 01-24-23, 06:47 PM
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Kobefan: Quick, permanent fix is a tempering/mixing valve. installed on water heater line to faucets and showers prevents dangerous over/high temperature water.

Most have dial adjustments to automatically that mix cold water with hot to limit temperature to say 120F.

There are many types:

PJmax voted this post useful.
Old 01-24-23, 09:13 PM
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Welcome to the forums.

Doug and I don't always agree with each other but I do here.

Here's your problem. You have what looks like a boiler that supplies DHW and heating hot water. You only want 120-130f for DHW but the boiler needs to raise the temperature to supply heating hot water. That is a common problem when the boiler supplies the DHW. Many people will have a separate storage tank installed that will supply correct temperature DHW regardless of boiler temperature.

The other method is to use a tempering valve like Doug mentioned. It takes the boiler water and automatically mixes it with incoming cold water to maintain the set temperature.
Old 01-25-23, 07:57 AM
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Look on scalding water as a hazard and tempering/mixing valves as safety/backup feature when things go bad.

DH home has tankless coil with pump circulating 140F to 170F water to inlet on 30 gallon storage tank., Pump is activated by aquastat in tank,

Faucets and showers draw water from tank .outlet.. It things go bad, thermostatically controlled tempering keeps temperature below 120F

In summer directly heat tank with gas. Cheaper than oil burner. Call it a hybrid system.

Last edited by doughess; 01-25-23 at 08:14 AM.
Old 01-26-23, 01:35 PM
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What am I missing here. Where is the DHW tank or flat plate. Where is the DHW coming from?
Show pictures where the DHW is coming from. A tank aquastat should keep the DHW closer than what you are claiming. I am in agreement of the mixing valve but still concerned where DHW is actually coming from.

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