carrier one pipe v. two pipe system

[sebastian]

I am having a 4000 sq foot, open concept, two storey house with basement custom built in Toronto, Canada. Due to health issues and an oversized wood-burning fireplace, air flow and quality is a serious concern. The plan is to install a premium humidifier, air clearer, hrv, and 90% EFF carrier furnace. The furnace the builder normally installs is a carrier 58MSA120, which is a one-pipe system. My research indicates that a one-pipe system is inappropriate because it uses inside air, and that I should get a two-pipe system. The builder and the sub-contractor disagree. Any advice would be greatly appreciated.

[BaldLoonie]

One pipe systems cause infiltration which raises your heating bill and can be drafty. Using very polluted indoor air is worse on the furnace that using somewhat less polluted outdoor air. I think about everyone on here will agree that 2 pipe is better.

[jrbenny]

Originally posted by BaldLoonie
One pipe systems cause infiltration which raises your heating bill and can be drafty. Using very polluted indoor air is worse on the furnace that using somewhat less polluted outdoor air. I think about everyone on here will agree that 2 pipe is better.

Yep.

[sebastian]

Thanks for the quick response. A follow-up question: to get a two-pipe system, I need to upgrade to the next model in the "comfort" line (the 58MCA). The question is whether to also upgrade to a model (in the "infinity" line) with variable speed. I have read all the posts here, which suggest that variable speed will reduce noise but not increase efficiency, and comes with a higher repair cost. Is there any reason other than noise reduction to upgrade to variable speed, e.g. wood-burning fireplace, compatibility with the air cleaner/humidifier?

[jrbenny]

Two-stage heat is more comfortable. Variable speed may gain you a point or two in SEER (air conditioner "fuel economy").

I'd look at the MTA (two-stage heat, standard motor) or MVP (two-stage heat, variable speed motor).

[mayguy]

Since you are from Canada, you are best to go two pipe venting.. Like bald said, furance should last longer since you are pulling in the fresh clean air all winter.. Not the glue, paint, fabric softner, and what not in the in the burner.

I would suggest the two stage with the harsh cold winters.. paying for the two-stage comfort is well worth the money! If you do go with the MVP, make sure you get the infinity stat!

[t527ed]

2 pipe v drive

[sebastian]

Thanks, two decisions made: two-pipe system with two-stage heating. Only remaining decision is with respect to variable speed. Can you please clarify what you mean by MVP "infinity stat"? Also, do you think that the noise reduction and (possible) SEER benefits justify the extra cost of the MVP? I also see that the MVP comes with a humidifier. Am I correct to assume that if I go with a lower carrier model I will have to spend the extra money on a comparable humidifier anyway?

[2hot2coolme]

Do you want to be able to hear when your system comes on? NO

VS systems are by far the most energy efficient & the quietest, I personally don't want to hear when my system comes on...just feel it

[northof49]

In Western Canada (can't speak for Ontario) a combustion air vent is code, minimum 6 inch I think. Now if you have outside air available to your furnace why would you need a two pipe system if the furnace is designed for a sinlge pipe?

Not trying to start a war............just wondering.

North

[Black Adder]

If you have health concerns and are using EAC, UV light or Heppa filters, definetly go with the variable speed unit. You will want to be running a constant fan for continuous air cleaning and humidification. With the variable speed running full time it will be barely noticable but will due an admirable job of helping with humidity levels and air cleaning. As for 2 pipe over 1 pipe, 2 pipe system for sure, you are trying to control your indoor environment as much as possible and with a single pipe you still need combustion air. It is using indoor air so therefor it is putting a negative pressure on the home and pulling unfiltered, high or low humidity air in. If you have no other NAFFA in the home you can do away with the combustion air duct that is currently in the home. Might recommend an HRV to help with the home ventalation as well.

[jrbenny]

Originally posted by northof49
Now if you have outside air available to your furnace why would you need a two pipe system if the furnace is designed for a sinlge pipe?

So, you can quit sucking cold air into your home which increases your heating costs.