Need info on Amana furnace...........(Starch)

John Starcher_4

...as it is an LP application. Jumpering the W1-W2 has been discussed, and we very well may try that, but I'm seeing very extended run times even with both stages active.

John Starcher_4

I replaced......

...a furnasty a couple years ago for a client. It was an Amana #P99616047, burning LP gas. I got the model number from a note on an old work order we had on file, but have no idea what BTU rating the furnace had.

My heat loss calcs were 51K at design. The home is not normally occupied during the winter, but this year the guy came up to spend the holidays. The problem we're having is that it takes a VEEERRRRRRRY long time to satisfy the stat. New furnace is American Standard 2-stage 60K. I have verified gas pressures, etc. and the furnace is operating properly, as far as I can tell.

HO thinks the furnace is too small, and I'm starting to agree with him. I'm going to redo the heat loss calcs to see if I missed something in my original ones, but I'm curious to know what size the old furnace was.

Can anyone help a brother out??????

Starch

allan_7

I think

that the p# is a production code and may not yield sizing.
Might want to try the Goodman people since they own Amana I think.

If it is a two stage you might want to try a two stage stat and get the second stage to latch in on a tstat command rather than the on board algorithim.

You might be able to jumper W1 to W2 to check if you are getting full capacity and clock the meter but check with Amana/GMC or Tim.

Good luck, bro.

Matt_67

furnace

is this a 90% efficient or 80%.on either furnace the 1st stage is around 32-36000btu,this is kinda low, if you took out a standard 75,000 btu with 60,000btu output.so if it runs on low stage at 30,000 btu a long run time is part of the design.not familiar with a/s,is there a 2 stage stat? if not some furnaces have a low stage run time setting,if you could decrease the 1st stage run time,it might help.what is the temperature rise?is it low?what speed is the blower on?how many speeds does it have?what is the size of the main supply duct off of furnace?

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joel_19

response time

I would first look VERY carefully at your duct system. With my Blower door and duct testing method I frequently see ductwork loosing OVER 30% of the energy produced. That coupled with WAY to small returns on most systems will do you in.

Sure you could slap in a bigger furnace and look like a zero Or.... You could hire a duct pro to analyze those ducts and possably fix the ducts saving the client big energy dollars and your but at the same time turning you from Zero to Hero!! having the proper testing instruments is key as it allows the H.O. to see what is going on.

Also could sell them the Honeywell TAM system pretty short money and allows him to phone the stat and turn it up before they drive up giving the furnasty a head start,plus they can dial in any time and check temps which everybody loves.

Silver linings do exsist in dark clouds my friend.

John Starcher_4

Joel...

....I suspect the duct system as well. I crawled under the house to see if any ducts had come loose, etc. and was amazed at how warm and "windy" the crawlspace was!!! I don't have a blower door kit, but it doesn't take a rocket scientist to see that the air distribution system is at least part of the problem. I think I'm going to try and push him towards addressing the ducts before we just go and slap a different furnace in.

I think we neeed to return to ground zero, and perform a follow up heat loss calc, along with verification of the duct system. The returns are, I believe, adequate in size, but I don't want to leave anything to chance at this point.

scrook_2

Answered your own question...

... you missed the crawl space load when you did the heatloss?

Seal, then insulate the ductwork in the crawlspace & I'd bet the problem goes away.

John Starcher_4

I think you're right.

I'm sure that I didn't take into consideration the unusually large duct losses.

I was hoping to be able to find the capacity of the original furnace, just to have a point of comparison.

Thanks to all for the replies.

Starch

Canadasteam

Amana furnace

I would start again and get the orifice size(s) from that appliance and the operating manifold LP pressure, then grab a consumption chart from a site like engineering toolbox and figure out the actual comsumption. Might really shed some light on the whole situation.

Good luck

Jeff_108

had same problem with general, but we installed the goodman. size was right, kept going back checking temps, and refer. 2 years later we finally looked in attic. NO INSULATION??