HVAC experts! How do I warm/cool my space?
September 13, 2016 8:31 PM   Subscribe

So, I bought an old building. It currently has a fitness centre (which I own) and two (rented) apartments in it – with room for a third. It has moderately inadequate heating and cooling right now, and nothing in the new potential space -- so I'm looking for solutions to heat and cool it. More below the fold.

Building of a variety of ages as it was added on to, but mostly upgraded. Downstairs is approximately 3000 sq.ft. (2000 gym, 1000 empty space), upstairs is approximately 1500 sq.ft. (750/750 per apartment). Currently, there is a single forced-air furnace with air conditioner attached, supplying heat/air to #1 apartment, gym and #2 apartment.

Consensus right now is that the furnace/AC is modestly over capacity, with the addition of #2 apartment last year (there are currently two forced air vents into the apartment).

I'm planning to convert the 1000 sq.ft. space into another apartment (#3).

Notable features/information:

(a) the current system doesn't have the capacity to support a third apartment;
(b) I have decent access (mostly) to the #2 apartment (upstairs) through the floor from the empty space (#3 apartment). Assume that there is space both inside and outside the building to support any heating/cooling options;
(c) I live in NW Ontario, which requires the ability to fight off both 30C summer temps, and -40C winter temps. I also have very expensive electricity, so it's not the first choice (necessarily), unless it's vastly simpler;
(d) I have close access to natural gas, water and enough electrical capacity to heat/cool these spaces;
(e) if it's possible to heat/cool apartment #2/#3 together, or independently, easily, I'm down with either option, but cheapest is better (I can deal with the thermostat in one apartment controlling the temperature in both). Currently, the gym controls the thermostat for both itself and apt#1, and it has worked okay.

I'm pretty handy, so I'm not afraid of any option, but I just don't know what I should be considering (forced air, electric, radiant, etc.). I plan on consulting local installers to meet code and do the hard stuff, but also want to maximize what portion of the labour I can do myself.
posted by liquado to Home & Garden (3 answers total) 1 user marked this as a favorite
Electric baseboard heat is vastly simple (any moderately electrically hand person can install electric heat); but probably not worth the on-going expense.

Gas fired radiant with mini split A/C units in each apartment would be the best but it is also pretty expensive to retro fit unless you can pour a lightweight aggregate in the upstairs apartments. It would also mean closing the commercial space for least a couple weeks and more realistically a month.

Realistically though if the current HVAC was good for the gym+ apartment #1 before the addition of apartment #2 I'd probably just revert the system back to doing that half of the building with the installed equipment and then add a second forced air furnace and A/C unit to heat cool apartments #2 and #3. One caveat is at some point with buildings of residential occupancy where a number of units share a forced air system code requires installation of fire shutters in the ducts between units. I'm 99.9% sure that would not apply in your case of two furnaces each feeding two units but you want to check with your building department before proceeding.

I'd also calve off part of the 1000 square foot apartment as a mechanical room to install the HVAC; water heating and telecomm and possibly electrical equipment.

Alternatively depending on the layout you could install two heat cool units (like you see on the roofs of low rise commercial), one each to condition apartment #2 and apartment #3 on the roof of each apartment. This will save you floor space that would otherwise be taken up by the furnace and will give individual thermostatic control to those two apartments. However one big unit is usually more efficient than two smaller ones and the one big unit will probably be cheaper.
posted by Mitheral at 9:02 PM on September 13, 2016 [2 favorites]

Because the HVAC needs of a gym are so different from those of an apartment, my inclination would be to use the existing system for all three apartments and reconnect the gym to a new system, if the layout allows. If you can zone each apartment, even better.
posted by sepviva at 2:46 PM on September 14, 2016 [1 favorite]

what is the state of the insulation/air sealing? upgrading the insulation may make barely adequate, adequate.
posted by ennui.bz at 6:13 PM on September 14, 2016

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