AboutJ Cook Expertise With 25+ years experience, I am familiar with residential, commercial, and industrial HVAC equipment including but not limited to boilers, chillers, reciprocating and screw compressors. I am trained in all manners of control wiring.
Experience I currently have three HVAC licenses and Refrigeration license by the State of North Carolina. I have been in this field for over twenty years. I have been a service technician for a contractor and also worked at a state college in the repair and maintenance of steam lines and equipment. I am currently the Building Maintenance Superintendent for a municipality.
This question stems from a Q&A I had with another expert earlier this evening... here is a copy of that...
Question Hello,
I am in a new construction home and find my furnace running constantly. I only keep the temp at 68 and it still does not help. I went into the crawlspace to find it was fairly warm and my heating ducts are NOT insulated. I was wondering if the HVAC guys were supposed to do this! I think this may be why parts of my home are cool and the crawlspace is so warm. Should I be questioning by builder? I have literally been in the house a month and will be upset if this is something THEY should have done. Any insight would be greatly appreciated.
If you have metal ducts,it's possible you have insulation on the inside of the duct. It's not uncommon to insulate the inside instead of the outside.No mention from you if the ducts were excessively warm, only that you stated the crawl space was warm.Doesn't necessarily mean that the warm crawl space is caused by the duct.
What I would do is run only your blower fan ( on your t-stat put the fan from "auto" to "on" ) and if your indoor fan starts put an accurate thermometer on your return air grille(s) and note temperature then move thermometer to a couple different supply grilles and note temperature difference between the return(s) to supply(s). they should be the same or only a slight difference ,if you have a large difference then you have outside air mixing in with your return air. And your return duct has leakage and not sealed . That may be one reason why your unit runs constantly.No mention from you where the Air handler is located , if it's a cold environment you could be sucking cold air in.
If your duct work is tight another reason for long run time could be that the heater is undersized for the residence, or they put a two stage furnace in and your running on low fire all the time instead of high fire, basically running at half capacity.(talking gas furnace ) no mention of what type of heat you have, oil, gas, electric or Heat Pump.
Certainly query the Builder about your concerns(uninsulated duct work ) as everything should be under warranty still. He should send out the Contractor who installed the unit and check operation.(constantly running )Labor should also be covered under warranty.You should get something in writing as to what your heating unit is covered from the installing Contractor/Builder as to what is the heat exchanger warranty is also what is the parts warranty also what is the labor warranty.Also if you have Central Air what is the compressor warranty and parts warranty. If you do have central A/C and you have metal uninsulated ducts and the crawl space is hot in the summer your duct work may sweat and drip condensation onto the insulation and eventually a finished ceiling if your duct is above a finished ceiling.
Now here is the follow up question/information I have. I do not know how to perform many of the things he asked me to, but I do know that when I turned my heat on.. my metal ducts became very warm (which would imply to me that they are not insulated on the inside). Also, I have electric heat (if that plays into this at all). I just don't want to look like a fool calling my builder if this is in fact normal. I have a 2500 square foot home.. and my back family room (which is 20 x 24) is on a different thermostat. Any information or insight you can provide would be appreciated. Thank you for your time.
Nataile
Answer You did not say if you have a/c on this unit, but according to mechanical code, the duct system does not require insulation if there is no a/c. The reason for insulating with a/c is as the other expert indicated, it is to keep the ducts from sweating and creating a moisture problem. That being said, if there is no a/c, the ducts are installed by code, if you do have a/c, you have recourse in insisting the ducts be insulated. I am certain you are loosing a lot of heat by the ducts not being insulated. It will be worth whatever the expense to have a contractor install insulation on these ducts. Without insulation it will be simple to follow all duct sections to ensure there are no loose joints or open duct fittings before they are insulated. The unit very likely is sized correctly, but you are loosing so much heat without the ducts being insulated, the unit runs constantly as it is merely maintaining what the home is loosing in heat loss. I feel certain unless there is an equipment problem that insulating the ducts will 99% certainly cure the problem. Thanks J
