[baylie21]

Hello everyone.

We have an oil furnace and tankless/on-demand hot water system. If my terminology is confusing, we basically have an oil tank, the furnace, and a bunch of pipes running out of it in our basement.

We heat the home with wood, but the radiators all appear to work well when we have requested their help. Our problem lies in the master bath. This room resides farthest away from where the furnace is in the basement. They sit at opposite ends of the home.

Anyway, for the past year, the shower and bathtub in this room struggle to get anything beyond luke-warm water. We accidentally discovered awhile back that the shower temp improves dramatically when the heat in the master bedroom/bathroom (has its own zone) is turned on. Sadly, we have resorted to now turning the heat on to take showers as it's the only way to take one that is comfortably warm.

I have no knowledge of plumbing or heating so I don't understand what the problem could be. This problem was not present when we moved in so we do believe something has changed. Just not sure what

Any ideas would be greatly appreciated. Thanks in advance for the help.

 

[AllanJ]

1. The coil (heat exchanger, component where the potable water is heated) may have sediment inside or outside that retards the heating from the boiler water. Such sediment gradually builds up over time. The boiler hast to be drained and the coil dismounted and taken to a company that specializes in removing that kind of sediment, sometimes that does not work and y ou need a new coil.

2. There may be a separately zoned circulator that churns the water inside the boiler so hotter water gets at the water heater coil, and that has failed. Turning on a heating zone may also accomplish this churning.

 

[baylie21]

1. The coil (heat exchanger, component where the potable water is heated) may have sediment inside or outside that retards the heating from the boiler water.

2. There may be a circulator that churns the water inside the boiler so hotter water gets at the water heater coil, and that has failed.

Thank you very much for the help.

Would both of these be possible if all other areas of the home get decent hot water delivery?

 

[COLDIRON]

Boilers have controls on them called aquastats which controls the temp of the water for heating the house and hot water for personnel use.

The part that controls the hot water for personnel use might be defective, this control overrides the heating control for example if your house thermostat is all the way down and your not calling for heat the boiler still comes on and off to maintain hot water temperature. A good example of this is summertime when most people have their themostats lowest they still have hot water for personnel use.

 

[baylie21]

Boilers have controls on them called aquastats which controls the temp of the water for heating the house and hot water for personnel use.

The part that controls the hot water for personnel use might be defective, this control overrides the heating control for example if your house thermostat is all the way down and your not calling for heat the boiler still comes on and off to maintain hot water temperature. A good example of this is summertime when most people have their themostats lowest they still have hot water for personnel use.

Oh...that makes sense. So a normal functioning aquastat for hot water usually would provide enough heat/temp, but if it is malfunctioning or bad, turning the zone heat on might help overcome its deficiency?

 

[COLDIRON]

Yes sounds like the temp control for the hot water is set wrong or is not controlling the water temp and when you activate a zone the boiler starts on the zone control and heats the water by default because it's already inside the boiler where the heat is being produced from the burner.

 

[AllanJ]

Would both of these be possible if all other areas of the home get decent hot water delivery?

How long does the hot water last in the other areas?

Sediment in the coil or insufficient boiler water circulation about the coil may retard the heating so that you get a small amount of hot water that sat in the coil and then the coil can't keep up heating more water coming through. For the bathroom far away, the length of the pipe run cooled down the initial charge of hot water so you you feel is the lukewarm water that follows. Also if you have just a low flow then the water heating coil may succeed in getting the water up to temperature.

 

[COLDIRON]

If all other areas in the house get enough hot water I would look into the problem at the one trouble spot like a bad faucet with scald adjustment or something like that.

 

[baylie21]

If all other areas in the house get enough hot water I would look into the problem at the one trouble spot like a bad faucet with scald adjustment or something like that.

No area really gets all that hot, but areas that are closer to the furnace seem to perform better. Thank you for your help. I imagine this is something for the pros? I consider myself capable of doing some fix-it stuff, but I have absolutely no knowledge of oil furnaces.

 

[AllanJ]

Also try turning off the washing machine water supply when the machines are not being used, and be sure that all showers are turned off using their faucets and not a sprayer hose or shower head knob. Then recheck to see if the situation is improved. (Turning these things off lowers the chance that a defect letting cold water cross over and go the wrong way down the hot water pipe, and cooling down the hot water.)

(The washing machine water supply should be manually turned off all the time the machine is not in use anyway, to lower the chance of a flood from a burst hose.)