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-   -   In Trouble need 150,000 BTU's (http://www.diychatroom.com/f17/trouble-need-150-000-btus-80552/)

turbomangt 09-04-2010 09:38 PM

In Trouble need 150,000 BTU's
 
Our furance is 20 years old and needs replacing, the problem is our house is just over 4200SF and the builder did not 2 zone the air and heat we have a 150,000 BTU furance and so far the 2 guys that came over for an estimate says they do not make a high efficientcy furance in that size, one guy said he would try connecting 2 smaller units in parallel (however he never did that before) the other guy wants to redo the duct work and 2 zone it, (way too much $$$, we will never recop that cost ) my question is what can do if we just want to replace furnace with a better one,

Marty S. 09-04-2010 10:03 PM

Two furnaces with standard blowers can be twinned together easy enough.

hvaclover 09-04-2010 10:39 PM

Yep. and you will probably save a bundle if you go with 95% efficient units.

beenthere 09-05-2010 04:43 AM

A 150,000 BTU input 80% efficient furnace, is 120,000 BTUs output.
A 120,000 BTU input 95% efficient furnace is 114,000 BTUs output. Doubt you'll miss 6,000 BTUs.


A load calc will probably show that a 120,000 95% input furnace is more then enough heat for your house. You can do your own load calc http://hvaccomputer.com/talkref.asp and find out what size you really need.

2 furnaces can be twinned to get the size you need, if it would turn out that you need the full 120,000 BTU output. The new furnaces will have instructions how to twin them. Done right, you'll end up with a nice 2 stage heating system. And probably save a lot of money on your heating bill.

hvaclover 09-05-2010 12:01 PM

Quote:

Originally Posted by beenthere (Post 496117)
A 150,000 BTU input 80% efficient furnace, is 120,000 BTUs output.
A 120,000 BTU input 95% efficient furnace is 114,000 BTUs output. Doubt you'll miss 6,000 BTUs.


A load calc will probably show that a 120,000 95% input furnace is more then enough heat for your house. You can do your own load calc http://hvaccomputer.com/talkref.asp and find out what size you really need.

2 furnaces can be twinned to get the size you need, if it would turn out that you need the full 120,000 BTU output. The new furnaces will have instructions how to twin them. Done right, you'll end up with a nice 2 stage heating system. And probably save a lot of money on your heating bill.


Gotta put my two cents in here.
At that size furnace there is no wiggle room. The biggest they come is a 120k. and if for some reason the furnace does not push enough air(some of the 150k furnace came with a 1 hp motor) you won't have any recourse with the 120k even if it has a 1hp blower.

A twined system would be two stage with both blowers going at the same time, but only one furnace working under low demand needs.

This gives more flexibility and does not limit your options as a single system would.

as an example a Nordyn standard 90% at 120k has a 1 hp motor.

Two Nordyne 902% 72k have 3/4 hp.

The reason I am suggesting this route is that the size of the OPs home should have had two furnace on separate duct work from the beginning.

Having seen more than my share of bigger home with only one furnace.
I can say the duct work in every case did not distribute well, which is the reason two systems were needed on separate duct systems. The second story of the home was always too warm or too cool.

The twined system has more to offer in correcting the bad air flow.

It reduces electrical consumption on the blowers and only one furnace will run in mild weather with addtional fuel saving.

turbomangt 09-05-2010 12:49 PM

Thanks guys

hvaclover 09-05-2010 01:04 PM

Quote:

Originally Posted by turbomangt (Post 496264)
Great, now who is in chicago that wants to give me an estimate? or if you know someone that would be good also

Just ask around. Call a supply hose and ask them if they can give you the name of a quality contractor.

beenthere 09-05-2010 02:19 PM

Quote:

Originally Posted by hvaclover (Post 496248)
Gotta put my two cents in here.
At that size furnace there is no wiggle room. The biggest they come is a 120k. and if for some reason the furnace does not push enough air(some of the 150k furnace came with a 1 hp motor) you won't have any recourse with the 120k even if it has a 1hp blower.

A twined system would be two stage with both blowers going at the same time, but only one furnace working under low demand needs.

This gives more flexibility and does not limit your options as a single system would.

as an example a Nordyn standard 90% at 120k has a 1 hp motor.

Two Nordyne 902% 72k have 3/4 hp.

The reason I am suggesting this route is that the size of the OPs home should have had two furnace on separate duct work from the beginning.

Having seen more than my share of bigger home with only one furnace.
I can say the duct work in every case did not distribute well, which is the reason two systems were needed on separate duct systems. The second story of the home was always too warm or too cool.

The twined system has more to offer in correcting the bad air flow.

It reduces electrical consumption on the blowers and only one furnace will run in mild weather with addtional fuel saving.

Lots of "wiggle" room.

A 4200 sq ft house generally doesn't have as much outside wall per sq ft of house, as a smaller 3200 sq ft house. So often the heat loss per sq ft is much lower.

York PS9D20N135UP11 is 127,000 BTU output, and comes with a 1 HP blower motor. So does it 120,000 and 100,000 BTU versions(not saying the OP's house only needs a 100,000 BTU furnace).

yuri 09-05-2010 03:43 PM

Another idea is that if you upgrade windows and add some attic insulation you may get away with a smaller furnace and save LOTS of Dollaros $$$ and be more comfortable. There may be some home improvement/add insulation grants from your local gov't and or utility co worth finding out about.

yuri 09-05-2010 08:47 PM

Depends if he intends to stay there for a long time and appreciates less drafts and more comfort. Insulation and triple pane low e-argon windows are a wise investment. LOTS of rebates where I am for those improvements so why not take advantage of them. I hear it gets real cold in Chicago at times so those improvements will pay for themselves.

beenthere 09-05-2010 09:17 PM

Quote:

Originally Posted by newtech (Post 496498)
Maybe soooooo....

But he was asking about a furnace.... Not windows or insulation:wink:

True.

But, new windows can cut his heat loss enough that a new smaller furnace can save him enough on his heating bill. that they both pay for themselves in a short time.

Only thinking of a new furnace. Without giving consideration of what can be done to the house to save on heating and cooling cost. is a mistake many make.

Scuba_Dave 09-05-2010 09:29 PM

Agreed
New windows, doors & sill insulated in basement cut my heating bill in 1/2
Just the 3 basement windows & sill insulated made a huge difference
Cost for the basement maybe $250

I've continued to update the insulation in my house
Added a 250 sq ft sunroom & heating cost still dropped

Red Squirrel 09-05-2010 09:58 PM

Personally I'd go with the twin setup. The nice thing with that is if one furnace breaks down, you have redundancy. It may not be as effective, but it's better then no heat at all. Guessing they need to be wired in a special way so the blowers run at same time though, otherwise you'd just be pushing air in the return of the other furnace if one blower is off, or is there some kind of damper? Would be interesting to see a setup like this. I've been in a house that had two, but never noticed if the ductwork was connected in any way. It may have been two zones.

Scuba_Dave 09-05-2010 10:06 PM

Quote:

Originally Posted by newtech (Post 496537)
Can we stay on topic please....

Furnace replacement.....

Thanks

What is off topic ?
Simply replacing a furnace without looking at ways to cut heating costs is not a good idea

Scuba_Dave 09-05-2010 10:21 PM

Its all part of a load calc on a house
Right ?

If someone did not take this into account when replacing my system then I'd be stuck with an oversized 130,000 BTU system instead of the 68,000 system my house needs

Like it or not this will come up

Quote:

Originally Posted by turbomangt (Post 496052)
I need someone I can trust, referrals welcome, need advice...

Sounds like he asked for advice.....
So he is getting advice

Advice is advice
As long as it is all concerning replacing the furnace
We would be remiss to NOT suggest reducing the heating system he needs
THIS IS ON TOPIC
So STOP repeating to keep on topic


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