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Hot water heater in mechanical room

user-7573496 | Posted in General Questions on

During a gut renovation job in Kittery Point Maine, I’m moving the difficult to service components in the crawl space moved to a mechanical room we’ve built behind the garage. A well and pump firm will run a new water line from the well to the crawl space (below the foundation as before), then thru the crawl space to the mechanical room where they will hook up a constant pressure system. This was recommended by the firm and seemed reasonable.

The plumber then comes in to Pex the whole house, and will hook the water filtration system and hot water heater in the mechanical room, with a hot water loop back to the house because of the longer runs. This was recommended by the plumber,, and seemed reasonable.

I prefer a copper pipe install rather than Pex, but it has taken months just to get one plumber interested and with continued communications (I live out of state), and he is not interested in copper because “he doesn’t have time that copper installs take”, since he works alone. He recommended that I reach out to a larger firm if I insist on copper, but I have other deadlines approaching and have been assured that Pex for installs is pretty common now.

I’ll need to find the best approach to keep the mechanical room above freezing, but with an approaching install date, my “hot” item to work on now is to get more facts and take a decision on the water heater. For our needs, the plumber recommended a 60gal hybrid to also take advantage of an Efficiency Maine $750 rebate, which I do not believe I can since I do not yet live in Maine.

We don’t have any appliances purchased yet, so am weighing operating costs of electric vs indoor pollution concerns and cost if we have propane for kitchen oven, stove and the clothes dryer. I have not looked at these at all yet, and again, the hot water heater is the next decision. Just throwing this out there.

I’m going to have a large propane tank to supply gas for an outdoor Weber grill and a pizza oven hookup, and probably a whole house generator, plus possibly for the other appliances mentioned above.

For the hot water heater, would appreciate your thoughts on hybrid or not, propane or electric per my described situation. Thank you!

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  1. Expert Member
    Dana Dorsett | | #1

    How big is the mechanical room?

    Is the mechanical room (and it's foundation) insulated?

    Are there any mechanical systems in the room that is NOT water (heating/pumping/filtration/etc) related ?

    Is the garage insulated &/or heated?

    1. user-7573496 | | #3

      Hi Dana,
      I should have guessed there is a lot more to it. :)
      We have an unheated 22'x 22' garage, then the 18 'x 7' mechanical room behind it, then the 18'x7' grilling area behind that. Access to mechanical room is thru the back of the garage.
      A slab foundation was poured for the mechanical room, but concrete footings recently added for the new grilling area. The mechanical room floor is expected to be left as concrete due to maintenance needs of water filtration system - I think we have a floor drain in it also.
      The garage and mechanical room have been gutted of drywall, insulation and mouse poop. The garage has a bonus room above it that has been gutted also. I believe we were thinking of 5.5" dense pack cellulose for the whole house exterior 2x6 framing, which would include the for the garage, mechanical room and bonus room, and I think we have 2x8 rafters that can take 7' of closed cell urethane spray foam to get R-49. This based on an Energy Audit and recommendation, but nothing has been contracted for yet.
      The bonus room will have a Mitsubishi 12k BTU M-Series Floor Mounted Unit MFZ-KJ12NA-U1 run by a Mitsubishi 30k BTU M-Series H2i Outdoor Condenser For 2-3 Zones: MXZ-3C30NAHZ2U1, Hyper Heat Cold Climate heat pump that is shared by the living space in the converted attic. The garage below the bonus room was not factored in for heating from that same condenser.
      The mechanical room will have:
       well water constant pressure system and it's wall-mounted electronics
       water filtration (well softener and conditioner, chlorinator, retention tank, salt tank)
       hot water heater
      I have not thought of what else would go in there, but the water filtration takes up a lot of room as spread out and we original planned for a well pressure tank instead of a smaller constant pressure tank.

  2. walta100 | | #2

    I am not sure it is a good idea to move the equipment out of the crawlspace.

    If you do this it will be necessary to heat this new space and if you just barley heat it is likely to freeze quickly when something goes wrong think power outage or heater failure.

    You are going to pay every month to heat the space to make life easier for the guy to work on the well pump for 2 hours over the next 5 or 10 years?

    Why not put the pump in the bottom of the well so you have a tank and a pressure switch in the crawlspace.
    Put a big door or hatch in the crawlspace life will be easy enough.

    I like my PEX but understand there are several different systems some are better than others. My PEX system has the fitting that fit inside the pipes and restrict the flow of water. I say if you go PEX up size the pipes one size.

    Consider going total electric and put a small tank on your gas grill. It is a sad day when you go to start the grill and see the knob is in the on position and the 500 gallon tank is empty and you are trying to remember if you left it on or if the neighbor kids thought it would be funny joke.

    What are you doing for heat?


    1. user-7573496 | | #4

      Hi Walter,

      The crawlspace required us to lift a hatch out of the living room, hop down to a chair, crawl for 20' in dirt and mouse poop etc, duck under a beam, then address the pressure tank, then crawl another 20' to the water conditioner for maintenance. Call me a wimp if you must, but not something I enjoy doing. I will pay every month for the ease of having it central in a mechanical room that makes access and servicing easier. I will take advice on how to best do that insulating and heating though :)
      I am relying on the advice of the plumber who was recommended by a couple other area plumbers who likewise do not have time for a whole house project now by themselves. My contractor who normally has done all my plumbing (but for this we need a permit) also said "he knows his stuff". Thanks for the info on the PEX sizing.
      Since I am not the only one in the family, I don't get final say-so on what kitchen appliances are electric or not. I might be able to sway choice towards electric, especially with my allergies. This is all just part of the big picture of things to figure out, but need what to do for the hot water heater first.
      I'm not adverse to continue to using propane tanks for the grill as we have been doing for years, but since I am probably adding a generator and a pizza grill, it got me thinking about what else could be propane "driven". First decision upcoming is hot water heater.
      I believe there are concerns about placement of hybrids to be most effective, and I can see that if I have hot water heater in mechanical room, then it is more than just keeping it above freezing.. that is less efficient that say placing it in the attic or bonus room. Depending on the answers I get here, I might be swayed as to type of hot water heater and it's placement. I currently have an electric hot water heater in the unfinished attic right now.
      I have no comparable to know what electric costs are in that area. I know I pay a lot for electricity when my contractor is working onsite, lol.
      We removed an smelly oil boiler in garage, the oil/kerosene tank behind garage, the hydronics baseboard heating for first floor, the ill-placed wood stove in kitchen, the fireplace and chimney that obstructed room improvements on all floors and attic. We might put an efficient wood stove in the corner of the first floor living room for ambience, but the whole house will be Mitsubishi H2i HVAC.
      One side of house: Mitsubishi 48K BTU MXZ-8C48NAHZ condenser, a 24K BTU SVZ-KP24 air handler and EH05 5KW duct heater and a Honeywell 150CFM ERV in crawl space, ducts on first floor, 12K BTU ceiling cassettes in upstairs master bedroom, 9K BTU ceiling cassette in other two upstairs rooms (guest bedroom, and office).
      Other side of house: 30K BTU MXZ-3C30NAHZ2U1 condenser, and for both the attic and bonus room above garage, 12k BTU floor endpoints MFZ-KJ12NA-U1

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