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Posted by RBM on May 11, 2008, 10:39 am
>
>>
>>>
>>>>
>>>>> There is a boiler in one wing of a home I own that has a tankless
>>>>> water
>>>>> heater.
>>>>> This wing of the house is closed off and not occupied. I only run the
>>>>> boiler
>>>>> enough to keep pipes from freezing in winter. I would like to
>>>>> disconnect
>>>>> the
>>>>> domestic hot water since it sometimes makes the boiler run even though
>>>>> there is
>>>>> no use for domestic HW in that part of the house. Can I simply cap off
>>>>> the
>>>>> cold
>>>>> water supply to the exchanger, drain it, and forget about it, or do I
>>>>> need
>>>>> to
>>>>> remove the coil?
>>>>
>>>>You could do any or all of the above, but it won't stop the boiler from
>>>>running. The easiest thing to do is shut the power to the boiler when
>>>>the
>>>>heating season is over. The other thing you can do is turn down the
>>>>aquastat
>>>>that controls the domestic hot water. This is sometimes a separate
>>>>device
>>>>piped into the boiler's water jacket, and on newer boilers it's often a
>>>>triple aquastat relay, which will have a low temperature cut in and a
>>>>high
>>>>temperature cutout within one box. In either case, just turn down the
>>>>cut
>>>>in
>>>>control as far as it will go, and the boiler shouldn't fire unless a
>>>>thermostat calls for heat
>>>>>
>>>>>
>>>>
>>>
>>> Thanks. Are you saying that turning that control down all the way won't
>>> affect
>>> the boiler functions of heating of the house? That almost seems too
>>> easy.
>>> I
>>> thought that control would affect the water temp to the baseboard
>>> heating
>>> circuit as well.
>>>
>>> I do shut down the boiler as soon as danger of a hard freeze is over.
>>> All
>>> the
>>> upper floor's domestic water plumbing and baseboards are empty, so I
>>> only
>>> need
>>> to heat the basement slightly to avoid damage to the foundation. I'm
>>> just
>>> trying
>>> to save as much oil out there as possible, and don't want to use any oil
>>> for
>>> heating domestic hot water that nobody needs.
>>
>>Without knowing the controls you have on the boiler, I can't say for
>>certain, but a typical modern boiler equipped with domestic coil, will
>>have
>>a triple aquastat relay, and the low temperature cut in is only to
>>maintain
>>tank temperature for the coil. The heating thermostat(s) will shunt the "T
>>T" terminals in the relay and fire the boiler overriding the low temp cut
>>in, and stay fired until the boiler reaches the high limit, or the zone
>>calling for heat is satisfied
>>>
>
> Thanks very much. The boiler is only a year old, so I imagine the controls
> are
> what you are describing. To be safe, I'll try changing the settings, and
> wait
> around to make sure everyting is okay before walking away from it.
All you have to do is turn the low temp cut in all the way down, then turn a
heating thermostat up and the boiler should fire, unless the tank
temperature is already at the limit, in which case it'll fire after some hot
water circulates, dropping it's temperature
>
>
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