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critterdoc
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| Joined: | Wed Aug 13th, 2008 |
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Posted: Thu Aug 14th, 2008 01:48 pm |
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We have an early 70's Kohler oval bathtub which holds in excess of 100 gals in an outside-opening utility closet with double louvered doors. My wife likes it hot for soaking arthritic bones. Tankless is not possible because of the the gas line is 1/2" gas line and there is no possible way to rerun a 3/4 gas line without major mods to the flat roofed concrete block structure. Maximum functional width of the heater closet is 24" which greatly limits tank capacity.
Specs on the A.O. Smith "Power-Vent" GPHE-50 and "Power Direct-Vent" GDHE-50 suggest that one or both might be a solution to getting 80 or more gals of hot water into the tub quickly.
I'm not clear about the mechanics of "condensing" hybrid heaters. What volume of condensate will be produced per unit of time when the heater is operating? How does it exit the device and can it be gravity drained to the outside of the house through a floor level hole which could be drilled in the outside wall which would be very close to the side of the heater? The unit would be placed in a pan which would also be drained outside through the external wall at floor level.
Will the externally opening louvered doors for the utility room which will house the heater and the gas furnace/air-handler allow for enough fresh air or will be need to add ducts for intake air.
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eleent
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Posted: Fri Aug 15th, 2008 04:53 am |
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Hello: You might want to look into the AO Smith Vertex heater. It is a condensing type with fairly high BTU input. The specifics of hooking it up should come from AO Smith, either in writing or on the phone with technical support. It's too easy to mis-communicate those details. A completely different approach would be to put an instant heater on the tub. If the rest of the house doesn't need such a big heater, you might be able to meet demand with a standard heater for filling and a dedicated tankless unit for bringing up to temp and keeping the tub warm enough.
Yours, Larry
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critterdoc
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Posted: Sun Aug 17th, 2008 05:12 am |
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eleent wrote:
If the rest of the house doesn't need such a big heater, you might be able to meet demand with a standard heater for filling and a dedicated tankless unit for bringing up to temp and keeping the tub warm enough.
Thanks Larry.
The heater I need to replace services only the master bathroom with the large 100+ gal bathtub and one stand up shower that would never be used at the same time. What I need is approximately 90 gals of hot water as quickly as possible. The Vertex GPHE-50 or GDHE-50 might be the best solution but I have one other question that I cannot get a straight answer to locally - and that is what happens if you connect the qquivalent of a 15,000/17,000 - 199,000 BTU .05/0.6 to 9.4/9.6 GPM Rinnai or Takagi tankless to a 1/2" gas line instead of 3/4" line that product specs all appear to call for in South Louisiana where winters are quite mild?
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eleent
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Posted: Sun Aug 17th, 2008 05:37 am |
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Hello: Basically the most you can get from a 1/2" gas line is 80,000 BTUs. It's a figurative brick wall 
Yours, Larry
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