Heating doesnt work-works for 10 mins n then cool air.

Reply

  #1  
Old 01-30-13, 12:37 PM
Member
Thread Starter
Join Date: Nov 2009
Location: New York
Posts: 4
Heating doesnt work-works for 10 mins n then cool air.

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. I will be uploading pics. Would the unit size blow out my AC condenser? is it really that bad to have a big unit? whats the probs it could cause.Any info would help me out.

Thanks
 
Sponsored Links
  #2  
Old 01-30-13, 03:21 PM
Member
Thread Starter
Join Date: Nov 2009
Location: New York
Posts: 4
Picture link

ImageShack® - Online Photo and Video Hosting


please see the link for pictures. any info would be helpful.

thanks
 
  #3  
Old 01-31-13, 05:00 AM
hvactechfw's Avatar
Member
Join Date: Jan 2011
Posts: 6,245
disregard any and all ac questions and focus on the heating problem. How cold is it outside? You have a condesning furnace in an unconditioned space (no, no). I would make sure the drain line is not plugged (with ice?). That sounds way too big for that space, but I don't know anything about your home. GET A NEW CONTRACTOR!!!
 
  #4  
Old 01-31-13, 05:10 AM
Member
Thread Starter
Join Date: Nov 2009
Location: New York
Posts: 4
thank you for getting back appreciate it. right now its about 50 degrees but its suppose to drop to 30 and low of like 20s in NYC "You have a condesning furnace in an unconditioned space (no, no)."-what do you mean by that. this furnace is only for my 2nd floor which has a sqft of about 1100. i know the return air issue needs to be fixed, i have gotten quote for 4k to fix up this whole mess. are the duct works sufficient i have 8 inch ducts and 2 10 inch ones for the biggest room?

thanks for your help
 
  #5  
Old 01-31-13, 12:15 PM
SeattlePioneer's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Jul 2007
Location: Seattle, Wa
Posts: 5,503
Condensing furnaces are highly efficient because they cause the moisture produced by burning natural gas to condense into liquid water, which then must drain away from the furnace and be disposed of.

If the furnace is located in an unconditioned space, the water in the furnace or drain lines can freeze, which will prevent operation of nthe furnace.

The installation instructions for most condensing furnaces warn against installing furnaces in unconditioned spaces for this reason.

Of course, your furnace might be OK. But the furnace needs to be installed according to the manufacturer's instructions or you might have problems with this kind of issue.
 
  #6  
Old 02-01-13, 07:59 AM
Member
Thread Starter
Join Date: Nov 2009
Location: New York
Posts: 4
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.
 
  #7  
Old 02-02-13, 03:21 PM
Grady's Avatar
Forum Topic Moderator
Join Date: Jan 2005
Location: Delaware, The First State
Posts: 13,926
I would get then furnace out of the attic. First of all it's likely way too big & secondly a condensing furnace (90% or more efficient) in an area where it can freeze is begging for trouble.
 
  #8  
Old 02-02-13, 10:31 PM
user 10's Avatar
Member
Join Date: Mar 2004
Location: NA
Posts: 1,838
Likes Received: 7
Wow that installation is absolutely horrible.

Installation issues aside, that furnace is at least two sizes too large - possibly 3 sizes if the space is insulated.

The two stage furnaces when used with a regular t-stat switch to high after a pre-determined delay (normally 5-20 minutes depending on how it was set up), so the problem might only be occurring when it tries to switch to high fire.

In your case, I wouldn't even bother with a two-stage t-stat -> one option is to disable the staging timer and lock it in low fire, since it's grossly oversized anyway.
 
  #9  
Old 02-03-13, 12:28 PM
Grady's Avatar
Forum Topic Moderator
Join Date: Jan 2005
Location: Delaware, The First State
Posts: 13,926
Horrible doesn't begin to describe that installation. How can anyone who does such work sleep at night?

I strongly suggest having that furnace removed & a properly sized 80% efficient installed in it's place. Here's a site where for about $50 you can run your own Manual J heat loss/gain calculation.
HVAC Software, HVAC-Calc for Heat Loss, Heat Load Calculations
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes