Question on bid for replacement furnace

[drbenjamin]

Guys

I am looking to replace the 22 yr old gas furnace in our home and I am concerned about the bid I received. I called up the company who had installed the original unit (when the home was built), and the person who showed up walked through the house, counted the registers, and wrote up an estimate. I was at work so didn't get to talk to him. Having learned here that a heat load calculation is needed to properly size a furnace, I called an asked if he intended to do one. He left me a voicemail claiming that
1) They had done the calculation when the house was built, and nothing had changed
2) He needed to get a minimum of 100cfm at each register, and he only had one unit that could deliver that airflow; if a heat load calc indicated that a smaller unit was needed he didn't have one that could deliver 100 cfm
3) It's a 2 stage unit he proposed so there's not as much danger of oversizing as the unit will spend most of it's time at the lower setting

The price is reasonable, and we've been happy with the service this company has provided during the 4 years we've owned our home. On the one hand I feel like the company has failed to demonstrate their competence in HVAC by giving a proper, calculated estimate, on the other I feel like the furnace they propose to install is probably just fine and I don't want to get hung up on formalities. What do you all think?
Thanks!

[coolwhip]

Me thinks that a 50ton/80ton system is waaaaaay to large for the house.:eek::D

[drbenjamin]

Me thinks that a 50ton/80ton system is waaaaaay to large for the house.:eek::D

OK, sounds like I'm misremembering his exact words. it was 50 (somethings) / 80 (somethings) :D

I'll check the voicemail and update my original post.

[m kilgore]

Ask them to produce the original load calc. If every register needs 100 CFM I would be very suprised. Bathrooms usually take very little. Other rooms should differ in CFM also.

With a variable speed two stage unit you need to be sized right in order to heat your house right. A 2 stage unit is for comfort and needs to be sized properly. You can't size off of each register needing to be 100 CFM.

Get another estimate.

[beenthere]

Doubtful that you need 100 CFM in the bathroom, and all the other rooms need the same CFM also.

As far as not being concerned about a 2 stage being over sized. You should be.

Get other estimates.

Since he said he needs 100 CFM for every register.
How many registers do you have.

A 40,000 BTU furnace comes with a 3 ton blower, which would be 1200 CFM, or 12 registers. :)

There is a chance, you being fed some BS.

What size is your home. And what area do you live in.

[drbenjamin]

THanks for the helpful replies guys. I double checked the voicemail, he is claiming that a 3.5 ton blower is needed based on the register, the smallest furnace he has w/ that sized blower is a 2 stage 60K input/88k input. We have a 2300 sq ft home in Redmond WA. I will definitely ask for the heat calc, but how do I evaluate it? Am I making sure that the furnace has the capacity for the coldest anticipated day? Or do I want to match the average expected requirement?
Thanks!

[beenthere]

The calc is done at the coldest temp for 97½% of time.

So you have 14 supply registers. LOL

That is not how you size a system for heating or cooling.

If you want, you can do you own.

Its a 50 dollar fee., Here is a link to it.
http://hvaccomputer.com/talkref.asp

[Mr Bill]

I guess if we took up for our tradesmen as much as we try and found something wrong in everything they do all the time there would not be so much paranoia with the public, of course some here would have to go into detox and we probably would not need this forum anymore. The guys changing out and existing furnace that has moved a certain amount of air for 22 years and the price is reasonable, and he has been happy with the service this company has provided during the 4 years he has owned his home and now we need to get NASA involved? :eek: :cool: :D


on the other I feel like the furnace they propose to install is probably just fine and I don't want to get hung up on formalities. What do you all think?
Thanks!

I think sir you already have your answer above. :D

[beenthere]

He's happy with their service.

So how does that determine if the furnace is oversized and using more fuel then it needs to or not.

[Mr Bill]

He's happy with their service.

So how does that determine if the furnace is oversized and using more fuel then it needs to or not.


O God! carry on soldier. :D I would be more concerned about CFM's or air flow than fuel usage that would tell you if it's oversized, anyway I did not want any pissing contest, I was really just making a remark that it would be good sometimes to stand behind some of our tradesman because..... we all can find "something" wrong with anyone's job trust me.

[Alden_Sloe]

We have a 2300 sq ft home in Redmond WA. I will definitely ask for the heat calc, but how do I evaluate it?
You can email me by bringing up my profile and just under the screen name is download vcard. I had a number of estimates done and can tell you who did/didn't do load calcs as part of the bid process.

[DanW13]

2) He needed to get a minimum of 100cfm at each register, and he only had one unit that could deliver that airflow; if a heat load calc indicated that a smaller unit was needed he didn't have one that could deliver 100 cfm

Sounds to me like your service guys only had one in his warehouse or shop that was enough BTUS to sell you with out having to go get the right size furnace for your home, so it seems to me like he is just trying to unload a furnace that he can't sell to other home owners, but thats just my opinion.

[beachtech]

2) He needed to get a minimum of 100cfm at each register, and he only had one unit that could deliver that airflow; if a heat load calc indicated that a smaller unit was needed he didn't have one that could deliver 100 cfm

Sounds to me like your service guys only had one in his warehouse or shop that was enough BTUS to sell you with out having to go get the right size furnace for your home, so it seems to me like he is just trying to unload a furnace that he can't sell to other home owners, but thats just my opinion.

you hae no idea what your talking about, do you?

[beachtech]

The calc is done at the coldest temp for 97½% of time.

So you have 14 supply registers. LOL

That is not how you size a system for heating or cooling.

If you want, you can do you own.

Its a 50 dollar fee., Here is a link to it.
http://hvaccomputer.com/talkref.asp

my load calc is free :D

http://www.hvaccomputer.com/hvac/sizer.asp

really, if you want to find your degree days you can find them here :) you will need them for your calc :)

http://www.degreedays.net/

[beenthere]

O God! carry on soldier. :D I would be more concerned about CFM's or air flow than fuel usage that would tell you if it's oversized, .

The company is sizinf by the number of registers.
Thats reason enough to be concerned about everything.

But putting it into money terms, gets a home owners attention quicker then saying, sizing by regs is not a good way.

[Mr Bill]

2) He needed to get a minimum of 100cfm at each register, and he only had one unit that could deliver that airflow; if a heat load calc indicated that a smaller unit was needed he didn't have one that could deliver 100 cfm

Sounds to me like your service guys only had one in his warehouse or shop that was enough BTUS to sell you with out having to go get the right size furnace for your home, so it seems to me like he is just trying to unload a furnace that he can't sell to other home owners, but thats just my opinion.



you have no idea what your talking about, do you?


Well you will just have to excuse him he thought he would just jump on the bandwagon. :D

[beachtech]

Well you will just have to excuse him he thought he would just jump on the bandwagon. :D

sorry, it must have been the big blue letters lol :)

[beenthere]

sorry, it must have been the big blue letters lol :)
What. Did you think the blue oval was coming out. :)

[Mr Bill]

The company is sizing by the number of registers.
That's reason enough to be concerned about everything.

I agree, but maybe he was really a smart tech and was tired that day and did not feel like doing a lot of splaining, and maybe the HO looked dumb enough to him to make a quick sell, pop the furnace in and be on down the road, hey you never know. :D

[beachtech]

What. Did you think the blue oval was coming out. :)

lol maybe something like that lol

that guy just gets on my nerves!! i dunno why, but he does a good job of it!!!

[beachtech]

I agree, but maybe he was really a smart tech and was tired that day and did not feel like doing a lot of splaining, and maybe the HO looked dumb enough to him to make a quick sell, pop the furnace in and be on down the road, hey you never know. :D

speaking from experience :confused: lol J/K

[Mr Bill]

speaking from experience :confused: lol J/K

You know I am man enough to admit I probably have done that once or twice in my 30 years. :eek:

[beachtech]

You know I am man enough to admit I probably have done that once or twice in my 30 years. :eek:

lol you, i doubt it, but if you say so :) how's things after the storm?

[ga-hvac-tech]

The first question I would ask the HO is what size furnace does the house have now, and what is the model and serial?

[drbenjamin]

I definitely appreciate the input, and the link to the free calculator. It was so easy to use, I can't imagine why the estimator didnt just do the calculation that way! :)

To Mr Bill's point, I wouldn't mind if someone had installed so many heaters in nearly identical houses that they just knew what the answer would be w/o going through the drudgery. I hope that's the case here; my plan is to educate myself a little more, call him back, and see if he can convince me that he is fully capable of sizing a furnace correctly.

Just for full disclosure, I asked for bids from 3 companies. One sent a person out who wandered around for 5 min, and never sent the estimate he had promised. One is the one we're discussing in this thread. The third came out, took loads of measurements and presented a very nicely documented proposal. I really want to go with the third, but their price was literally twice as much and well above what I have saved. So, if I can't convince myself that the affordable company is reliable and competent I'll have to hope I get another couple of years out of my old unit to save up.

[Mr Bill]

To Mr Bill's point, I wouldn't mind if someone had installed so many heaters in nearly identical houses that they just knew what the answer would be w/o going through the drudgery. I hope that's the case here; my plan is to educate myself a little more, call him back, and see if he can convince me that he is fully capable of sizing a furnace correctly.



Hey and I am totally with you there and remember your the Boss. :D

[drbenjamin]

The first question I would ask the HO is what size furnace does the house have now, and what is the model and serial?

I hadn't even thought to check! It's a Bryant 396GAW000075. The label says 75,000 BTU in, and Manifold Pressure 3.5 in WC. In the 4 years we've been here the only time it couldn't keep the house warm enough was when we had a major windstorm and the power was knocked out for 8 days ;)

One thing I also only appreciated recently is that there are a limited number of furnace sizes available. So, if my house has a heat load calc come in 4000 BTU lower than my neighbor, we'll probably end up with the same unit because the units aren't spaced 5000 BTU apart.

Thanks -

[beenthere]

So if they are proposing a 100,000BTU furnace. You now know that would be ovesized.

[drbenjamin]

So if they are proposing a 100,000BTU furnace. You now know that would be ovesized.


The one they are quoting is 2 stage; 80k in / 75k out and 52k in / 49k out. My old one is rated at 75k in / 58k out, so the output is right between the 2 stages of the proposed new one. Does that sound right?

[beenthere]

On the coldest nights. Did your old unit cycle on and off, or did it run constant.

[drbenjamin]

On the coldest nights. Did your old unit cycle on and off, or did it run constant.

I honestly don't know! I can barely hear it when it's running, I only know that it's cycling from the click of the ignition.

[DanW13]

Beechtech your right I have absolutely no idea what I am talking about but I can read, as least you could give me credit for that couldn't you !!! I suppose you read that entirely way different than everyone else right ?? Or are you just by default standing behind this service guy who gave this HO a rule of thumb estimate, and if you weren't in the bussiness and just a regular Joe HO how would you have read what he told this OP ? I call it like I see it and I just merely pointed out what this service tech said and the way he said it if the OP is stated the guy word for word I again see it as this guy has only one size furnace he was trying to sell the OP and wasn't willing to get the proper size. Again just my opinion, so there's no need for you to say the type of comments you do to me or anyone else who is merely stating there opinion.