Please help heat shooting cold air and water dripping furnance

1316 Views 12 Replies 5 Participants Last post by piyush22, Feb 1, 2013

piyush22

Discussion Starter · Jan 31, 2013

could someone please help me with my heating issues. i have a luxaire dual stage furnance 100btu ( my sq ft for my 2nd floor is only 1025) and the furnace is only for 2nd floor only. the model # is TM9T100C16MP11 -95% 2 STAGE PSC 100BTU 16CFM M. The ac condenser i have is a carrier- model # 24Abb336A0031010 which i believe is a 3 ton unit. (is that a problem the differences in ton btw furnance and AC, aslo do i need 100k btu for 1025sqft) the problem that i have is that my heat turns on for like 15mins and then shoots out cold air. and all i hear is the fan blowing, i dont hear the noise of gas or anything. I checked the code it says that is something to do with pressure switch. Also my ac/heating contractor screwed me up big time and dont think did a proper install. he cut a hole next to the return air bec i think the return air vent was 2 small. Now i been getting quotes to redo everything for 3-4k. Any info would help me out.
also what can i do in regards to the oversized unit? would it cause me problems ? or would it blow out my condenser?this unit is like 7 months old prob and i know he didnt do a good job and we had words with him and he said he was going to fix it up. also i have little water drops dripping inside the unit prob from condensation which is prob due to pressure switch issue. any suggestions would be helpful. based on the models i gave would i have any issues with AC in the summer ? also the duct size is 8 inch and 2 10 inch one going into the master bedroom. see link for pics Thanks

http://imageshack.us/photo/my-images/856/img4684xj.jpg/

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Technow

· #2 · Jan 31, 2013

Where did you find that "contractor"?

That 100k furnace for 1000sqft is probably okay at the south pole. And 3 tons for 1000sqft is good for the sahara desert.

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piyush22

Discussion Starter · #3 · Jan 31, 2013

i no dude, i got my 2nd floor done so it was all included in the price with the contractor. any suggestions ?

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yuri

· #4 · Jan 31, 2013

I heat my 1400 sq ft WELL insulated house with 70,000 BTUs in -40F Canada so unless you have no insulation then that unit is grossly oversized and will die a quick death from overheating the heat exchanger and cycling on the limit control etc. Get a different contractor to size it and the ductwork properly is the only solution.

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old_squid

· #5 · Jan 31, 2013

My mother taught me if you can't say something nice, to not say anything at all. :whistling2: Like the above poster said, the equipment is more than likely too big for your space in both heating and cooling modes. The duct work......... well that's just ............. wrong!

Hire another contractor. Make sure they do heating and cooling load calculations to be able to prove to you the equipment sizes they are installing are correct. Have them show you the calculations that show that the duct work they plan on installing is all sized correctly for the correct sized equipment.

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Technow

· #6 · Jan 31, 2013

old_squid said:
My mother taught me if you can't say something nice, to not say anything at all. :whistling2: Like the above poster said, the equipment is more than likely too big for your space in both heating and cooling modes. The duct work......... well that's just ............. wrong!

Hire another contractor. Make sure they do heating and cooling load calculations to be able to prove to you the equipment sizes they are installing are correct. Have them show you the calculations that show that the duct work they plan on installing is all sized correctly for the correct sized equipment.

x2

and if the contractor that does this and says a 45000 btuh furnace is enough and another contractor comes along with a cheaper price and sells you a 60,000 because "its bigger" don't do it. :no:

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jagans

· #7 · Jan 31, 2013

Clogged Condensate Trap and drainage lines. No draft, so pressure switch is not making.

Kill Breaker to furnace

Clean trap, drainage and vacuum lines with warm water dish soap and bleach in laundry sink. Clean out orifices where vacuum lines attach to pressure switch. Suck out secondary heat exchanger with shop Vac. Pressure Switch Looks like a Black or Silver Hockey Puck with two electrical leads and two hose bibs. Also clean electrical leads.

Prime Trap, Then Turn on Breaker. Raise temp at stat.

Report results.

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piyush22

Discussion Starter · #8 · Jan 31, 2013

thank you all for your help, ill be prob getting the whole thing done again as there are soo many mistakes.

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piyush22

Discussion Starter · #9 · Feb 1, 2013

thanks guys, i had a hvac guy come in and knew what he was talking about and told me that i would need to have a plenum for the return air and has to be bigger and the drain issue he would fix up, re-pipe it where its needed and add a bigger tray re-wire the unit, add a 2 stage thermostat and add a new vent in hallway also add a extension for plenum for the duct works so that there is less compression in the flexs. also he said we can add 2 vents in attic since i have no insulation and heat which would kinda help me out with the coverage of the sq ft since my attic is about 700 sqft. and he did tell me the unit is oversized. all this he said would come out to 3500. is that a reasonable price. he said if i wanted to change unit and condenser outside it would cost me 3k total for both units. so i am not going to change the units right now as i dont have that much money. so does the price sound reasonable to fix up all the issues for $3500.

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yuri

· #10 · Feb 1, 2013

hard to tell about the price but it is a lot of work and worth trying as it sounds like he knows what he is doing. with a true 2 stage tstat the unit may never go to high fire as it may be able to heat the area fast enough on low fire so you may get away with the furnace being oversized if he can get the ductwork to work properly and move more air. worth a try IMO. He should do a temp rise test when done and see if it can run at least 10 mins w/o cycling on the limit control which will show as an error code on the board.

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piyush22

Discussion Starter · #11 · Feb 1, 2013

thanks for your help guys

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jagans

· #12 · Feb 1, 2013

Yuri, He knows what he is doing by wasting fuel, and throwing heat into an unheated attic to propagate ice damming?

Help me out with this, will you?

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piyush22

Discussion Starter · #13 · Feb 1, 2013

i was intenting on putting a very small vent near the furnace only and prob wounldnt even heat up the attic at all prob but would help the pipe from freezing. but wire heat tape should do the job.

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