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My furnaces don't pass the safety test....

  • Last Updated:
  • Apr 24th, 2020 12:54 am
[OP]
Jr. Member
Oct 26, 2015
158 posts
36 upvotes
Calgary, AB
craftsman wrote: Actually, older mid-efficiency furnaces (ie those ones frequently installed about 20 years ago) are relatively simple beast so the reliability is probably higher than the current crop of high-efficiency ones.

The problem with the OP's furnaces is not the age of the units but the fact that they both failed their safety test!
Yep! At my previous house, I had a 24 yo furnace and it worked like a charm. All the service companies that checked it told me to def keep it. Different story with my furnaces now that are even known to not be that good in the first place!
Deal Guru
Jan 27, 2006
14869 posts
7821 upvotes
Vancouver, BC
engineered wrote: Agreed, I'm also running an 80% eff furnace from around 2005, so not much older. Everything is in good shape, but I don't like the waste and that it uses interior air. I might upgrade the PSC motor to a Mars Azure ECM motor to lower electric costs and allow a lower fan speed.
At that age, I would plan on the OE fan motor going soon anyway as mine did a few years back - bearings were going. I had to go to the US for a reasonably priced replacement motor so you might want to start sourcing it now and get one when things open back up.

I do agree with you about the waste and the interior air but at the end of the day, it will cost more to fix those two points that what it might be worth.
[OP]
Jr. Member
Oct 26, 2015
158 posts
36 upvotes
Calgary, AB
Is that common for companies NOT to perform a manual j? 2 out of 3 companies didn't...
Deal Expert
Mar 23, 2009
18409 posts
4762 upvotes
Toronto
Badiha wrote: Is that common for companies NOT to perform a manual j? 2 out of 3 companies didn't...
It seems most don't. I learned the hard way that it really is recommended.

For one part of the house which is about 2500 square feet with basement, I have a 3 ton AC. For the other part of the house which is a bit smaller at around 2100 (plus crawl space) but which has more windows (albeit with poor circulation in a couple of the rooms), I had guesstimated that the HVAC would quote a 2.5 ton for the AC. He came back with a 2.5 ton quote which seemed fine to me going by my online reading. But then he came back later and said he is going to put in a 3.5 ton instead "because there are so many windows". I didn't ask to see the calculations, partially because the cost wasn't going to be much different, but in retrospect it seems clear that he had not done any calculations.

The 3.5 ton is installed, and while it doesn't have a super short cycle, it does cycle shorter than on the other side of the house, and the humidity is consistently about 5%+ higher in the summer. What this means is while it may be 45% in the main part of the house, it will be 50% in the side of the house with the oversized AC unit. However, on particularly humid days, it may go over 50% on that latter side of the house, which is not ideal. ie. The oversized AC cools too quickly so it doesn't stay on enough to remove the proper amount of humidity. It's still tolerable, and I just live with it, but when it comes time to replace it, I'll downsize. The furnace is only a couple of years old, but the AC is about a dozen years old. I wonder how long it will keep going, but I'm guessing I've probably got about another 5 years.
Deal Addict
Dec 19, 2009
3849 posts
1850 upvotes
Badiha wrote: Is that common for companies NOT to perform a manual j? 2 out of 3 companies didn't...
If the customer would pay for the Manual J calculations then more contractors would probably do them.
[OP]
Jr. Member
Oct 26, 2015
158 posts
36 upvotes
Calgary, AB
pootza wrote: If the customer would pay for the Manual J calculations then more contractors would probably do them.
Shouldn't that be included in every quote? I mean, one of the companies that came to our place did it for free. (They were the most expensive so that would explain it but still. You certainly don't want to install $10K furnaces if they don't even make sense)
Deal Addict
Dec 19, 2009
3849 posts
1850 upvotes
Badiha wrote: Shouldn't that be included in every quote? I mean, one of the companies that came to our place did it for free. (They were the most expensive so that would explain it but still. You certainly don't want to install $10K furnaces if they don't even make sense)
Most reputable/competent installers will know what size of furnace/AC you will need because of their experience and they probably have done multiple Manual J calculations in the past. A contractor would be foolish to waste 8 hrs of his time in order to do the calculations if he wasn't going to get re-reimbursed for some of it. Some will do it and include it in their quote, some will do it as an extra, some will not do it and try to be low bidder.
Sr. Member
Nov 6, 2009
987 posts
184 upvotes
engineered wrote: Agreed, I'm also running an 80% eff furnace from around 2005, so not much older. Everything is in good shape, but I don't like the waste and that it uses interior air. I might upgrade the PSC motor to a Mars Azure ECM motor to lower electric costs and allow a lower fan speed.
Thinking about doing the same instead of replacing the furnace and am expecting lower fan noise out of this ecm motor switch. Am I on rite track about noise? Also my fan makes small noise at start up (sometimes bit loud), probably the fan bearing or is it motor bearing?
[OP]
Jr. Member
Oct 26, 2015
158 posts
36 upvotes
Calgary, AB
pootza wrote: Most reputable/competent installers will know what size of furnace/AC you will need because of their experience and they probably have done multiple Manual J calculations in the past. A contractor would be foolish to waste 8 hrs of his time in order to do the calculations if he wasn't going to get re-reimbursed for some of it. Some will do it and include it in their quote, some will do it as an extra, some will not do it and try to be low bidder.
Makes sense! It kinda sounds mandatory in the US but not here.
Deal Expert
Mar 23, 2009
18409 posts
4762 upvotes
Toronto
When we did my basement renovation, we decided to move the furnace back several feet to open up the main basement area, because the previous design had a bigger furnace room than necessary and a huge laundry room. Our furnace was a single stage and roughly 15 years old and had needed some repairs. Instead of just moving it, we decided to replace it, even though it was still working fine after the repairs in the previous years.

We paid an HVAC engineer to do all the calculations. We went from a 100000 BTU single-stage unit to a 70000 BTU high efficiency modulating unit (covering about 2500 square feet over three floors including basement). As mentioned earlier, the comfort and noise are much, much better with the 30% smaller furnace. Also as mentioned, the house is moderately leaky. Not well sealed house by any means. House was originally built in the 1950s and a second floor was added in the 1990s.
Deal Addict
Dec 19, 2009
3849 posts
1850 upvotes
EugW wrote: When we did my basement renovation, we decided to move the furnace back several feet to open up the main basement area, because the previous design had a bigger furnace room than necessary and a huge laundry room. Our furnace was a single stage and roughly 15 years old and had needed some repairs. Instead of just moving it, we decided to replace it, even though it was still working fine after the repairs in the previous years.

We paid an HVAC engineer to do all the calculations. We went from a 100000 BTU single-stage unit to a 70000 BTU high efficiency modulating unit (covering about 2500 square feet over three floors including basement). As mentioned earlier, the comfort and noise are much, much better with the 30% smaller furnace. Also as mentioned, the house is moderately leaky. Not well sealed house by any means. House was originally built in the 1950s and a second floor was added in the 1990s.
The size of a furnace for heat loads is not based on the input BTU's ... it's based on the output BTU's.
Last edited by pootza on Apr 22nd, 2020 10:54 pm, edited 1 time in total.
Deal Expert
User avatar
Feb 11, 2007
15139 posts
16128 upvotes
Oakville
sonajatt wrote: Thinking about doing the same instead of replacing the furnace and am expecting lower fan noise out of this ecm motor switch. Am I on rite track about noise? Also my fan makes small noise at start up (sometimes bit loud), probably the fan bearing or is it motor bearing?
If running at the same speed then it won't be any more quiet, as the noise come from the blower fan, not the motor driving it (unless your motor is failing and making squealing sounds).
Deal Expert
Mar 23, 2009
18409 posts
4762 upvotes
Toronto
pootza wrote: The size of a furnace for heat loads is not based on the input BTU's ... it's based on the output BTU's.
Yes. I believe the original 100000 BTU furnace was 90% efficiency so 90000 BTU output I guess. The new furnace has a 66000 BTU input with 95% efficiency so 62K and change output. Roughly 30% lower maximum output.

The latter furnace was purchased based on upon the results of the heat load calculations done by the HVAC engineer.
Deal Expert
User avatar
Jul 5, 2004
25046 posts
4242 upvotes
Evil Baby wrote: To be fair, OP has two furnaces in the house, so OP could probably go a few days without one of them if needed.

At 23 years old, you probably should have expected to be replacing those furnaces pretty early on in the ownership of your house anyways.

Just get a few quotes and go from there.
Everything you need to consider is summed up in this post.
Hopefully you budgeted for new furnaces. After 23 years, it should be expected that the furnaces will die anytime.
Consider whether you need 2 furnaces or if you can make do with 1. Even if it requires duct and drywall work, might be a lot cheaper still. Can you close off part of the house? Lots of people do that.

Get a couple quotes and see what different options you have. If money is really tight, perhaps you can find a used pellet or wood stove and have that installed along with only 1 furnace. If you get a used one for a decent price, in a few years when you can afford another furnace, you could likely sell it for what you paid. You'd only be out the installation costs.
[OP]
Jr. Member
Oct 26, 2015
158 posts
36 upvotes
Calgary, AB
I can’t have just 1 furnace unfortunately given the layout of my place. I got all 3 quotes that I posted in the thread. I guess I was kinda hoping that these furnaces were as good as my previous one. (24 yo and still working like a charm! Being serviced every year with very small repairs) I was told by one of the furnace guy that these furnaces were not great so yep... indeed, I did expect to change them in 1-2 years. Now it’s more like this month! I’ll probably go with the Heil quote. It just annoys me like crazy that I did have to pay for repairs in the first place when these furnaces can’t be salvaged. My mistake. I’ll know better next time.

And nope, didn’t budget for that at all but I always have some extra money just in case so here you go!

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