Quest

For water heater: you have to be careful.

If your original/current one is a storage tank type heater (assuming it's natural gas type), then changing to tankless water heater may ended up costing you more RE: need to modify the exhaust vent pipe (B-pipe) and also need to have an external wall close by for your tankless water heater venting.

Ordinary/conventional storage tank type heater venting cannot be retrofitted/modified to vent for tankless water heater type... Cost to modify/re-run the venting if you run tankless would probably offset the savings from switching to tankless.

Also: It's not really that beneficial (*you don't save all that much) if your tankless water heater is to feed very long lengths of internal piping to bathrooms, kitchen sinks, etc. that are far, far away from it, for you'll lose a lot of energy (*in form of heat*) even by switching to tankless.

And then that's the need to reverse-flush with acid (vinegar, etc.) periodically to rid of water scales formed inside those tankless water heater in order to maintain max. efficiency.

An extremely well-insulated tank type storage water heater (assuming natural gas still) would be just as saving as tankless, only about 15% less saving.

Lastly: on natural-gas heater furnace: it's now federally mandatory to run 90%+ efficiency (AFUE) furnace throughout Canada, so single-stage, while it's been discontinued, is no longer advisable (*unless you have a very old venting system in your house, and routing a new furnace exhaust to outside deemed impossible). While I do see some ads/flyers advertising a single-stage, high efficiency (max. 80~85% AFUE efficiency) is still avail from some companies, it is, to be honest with you, best to go with 2-stage condensing furnace that are typically 95~97% AFUE efficiency) these days, for the savings are immediate and the benefits are far greater than that of retrofitting with a single-stage one, price difference (with all the provincal/Fortis/federal rebates combined) is only a few hundred dollars.

Pretty much all major brand names are fine (carrier, trane, Goodman, GE, Bryant, etc.) and quality are pretty much the same.

Q.

Quest

my family, relatives and friends all had their fair share of issues with certain shops that aggressively advertised in Chinese newspapers, or flyers that regularly shows up at your doorstep.

PM me and I'll give you my list (sorry, don't wanna offend anyone else even though there's no conflict of interest with me.

Q.

Quest

@OP:

While some sez that regularly air duct cleaning helps (? allievate any dust-related allergens, etc.), My experiences tell me that unless you've been using the cheepest, spun fibre-glass air filter in your furnace, otherwise: there's no need (IMHO) to do frequent air duct cleaning), so long as you are using decent air filter with filtration ability of MERV 5 or 7 or higher.

While I do understand the need for maintenance for any natural-gas furnaces,etc. fact is, as I can see that most high-end natural gas hot water storage tank heaters have their burner section sort of sealed, it leads me to believe that there's no need for frequent (once a year) servicing.... I would find a trustworthy heater technician (licensed) to do mine/ours once every 3 yrs or so, and will be fine.

Q.

BTW: most hot water storage heater (natural gas type) still uses pilot light, but with a piezo ignition to light it (with a sight glass sealing the bottom part of the burner section); whereas any recent hot air heater furnace (natural gas type) built/installed in the mid-80s are mostly mid-80s efficiency style with a hot element style ignition (no pilot lights).