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I have a new 5 ton hvac system where the heater side was replaced as well. The old unit heater worked fine, it would warm my house up to into the 70s even during very cold winter evenings. The new unit doesnt keep it above around 65 at night then struggles during the day to get it near 70 while we have the cold outside temps now of around 45 during the day and near freezing at night.
My hvac guy who did the work replaced the electronic control unit in the attic but this did not fix the problem. He has been called but always says he has customers without heat that need attention first then never gets to me. I dont think he has a clue what to do next.'
Any other forums I should put this question to? This was my best guess after exploring. Hoping a professional has run into this before and can guide me,
The unit is a high SEER one, its a trane, not sure what this could be? I have the set point at 71 and it wont get close to that temperature anytime in this cold. My other two units are on and working properly so the load space is not other than design. These are cold temps for us but never heard of anyone having this issue. The unti just licked on and is blowing hot air but it will shut down before it gets more than a degree warmer. What could this be?
Quote:
Originally Posted by Johnhw2
Well come to think of it the attic air handler was moved over a couple of feet to improve access to the unit. Used same duct work and thermostat is not nearer a vent.. But wil check this.
THanks.
Quote:
Originally Posted by Johnhw2
It is a natural gas heater. It serves the Family Room, kitchen, Living room, study, Dining room and breakfast room. Its the main unit in my home for most of downstairs other than a bedroom wing on another unit. The third unit is for two bedrooms and a game room and a media room all upstairs. We have high ceilings down in FR, Kit and LR. Also the house has two very open staircases that connect upstairs to the area the main unit serves down stairs. Hope that is clear
Without the model number of the Trane heater we're really taking stabs at a possible problem. The model can help us understand how the unit functions. It could be a T-Stat or control board issue even if the Tech cleared those. It could also be an air flow issue tripping the unit's shut-down.
Another weird problem and has happened with high efficiency condensing units is a blockage in the condensate discharge line. When the drain line blocks it backs up and can shut the unit down. These are typically tied to the drain line of the air conditioner evaporative coil located and attached to the heater cabinet. Don't know how your AC condensate line is routed but it is typical to run them to a bathroom sink drain line. Sometimes these lines are nothing more than rubber hoses which get crimped and can block it. Or the line could be blocked by normal sink use. These tend to be overlooked as the cause.
Your new unit appears to have been installed just prior to this heating season and this is the first year it is in operation? If this is a condensing unit did they even run a condensate disposal line from the heater? If so did they properly terminate it to the AC condensate line or is the connection blocked some how?
Have you tried shutting all three units down at their T-Stats and allow the house to cool. Then turn on just the problem unit to see if it would rise to the T-Stat set point?
Another possibility is a problem with the ductwork since the unit was moved. Is it possible you have significant leakage into the attic? The heater might be running its hardest to warm the air but reaches its burner temp limits and shuts off. Check the ductwork in the attic to see if there are any disconnected points or leakage at the air handler.
Thanks I will take a look for the model number and to be sure the attic is not where the heat is going now. Pretty sure it is not as the hvac contractor has been back to service things since this unit was installed a couple of years ago. It was not a huge issue before as we typically do not get as cold out in NTx as we are now,
I took a look and found one return duct, it is located in the ceiling directly over the thermo stat so if it is short cycling what is the cure other than move the return duct? Why would the old unit work ok this way but the new one doesnt?
Thanks for the valuable insights on this issue. Yes I have pounded the desk to my contractor but think he has exhausted his knowledge as his first solution was to replace the electronic control unit at the condenser. I will check to see what the condensation drainage looks like when up in the attic.
On the duct work possibility I should mention the AC uses same ducts of course and operates more efficiently than the old unit so doing as it should Also no condensation issues in AC cycle.
Could the issue be simple as a dirty air filter (although this issue has occured at all life cycles of a filter)?
If you have cathedral type ceilings I know those things to be a real pain. Warm air rises. You're heating all that air above you and it's not where you live. I've seen the problem before back in the 80s in a new McMansion. Unit ran all the time. If memory serves me the customer just had the fan on all the time to keep all the air circulating.
The most effiecient way to build a home is a small box shape. In colder climates the smaller the better. Russian homes are always small, do you want the heating bill for a 3000 sq ft house in an arctic enviroment with high ceilings?
I noticed you said it's colder than usual. Maybe there's no allowance for this built in.
Try taking the filter out for awhile and see what happens. If they're dirty they do restrict airflow. If it's been running a lot it will be dirtier too.
I have a new 5 ton hvac system where the heater side was replaced as well. The old unit heater worked fine, it would warm my house up to into the 70s even during very cold winter evenings. The new unit doesnt keep it above around 65 at night then struggles during the day to get it near 70 while we have the cold outside temps now of around 45 during the day and near freezing at night.
@Johnhw2 Your HVAC guy may have people without heat, but even without an ongoing service agreement his warranty on his inefficiently operating unit should still command reasonable attention. If HVAC guy has more business than he can handle, favorable reviews, referrals, etc. still matter. You're not freezing, but squeaky wheels reasonably get more oil! Without totally pissing off HVAC guy, you have plenty of ammo to chase him down and push for more tweeking of your new unit, duct work, etc. to better satisfy your expectations.
From a different comical angle, your message harkened up echoes of my old man's past reminders to "... put on a heavier sweater or long johns". Sort of polite, and less so at times. 70, during the day? 65, at night? Whoa Nellie!
Hopefully my wife doesn't read this message forum. Daytime, our Nest thermostat's set at Eco low 60 when we're out to a reasonable 65 and hitting a balmy 68 earliest and latest on the coldest of days. And, we're located in cooler climes than Texas. Nights, the Nest is always on Eco with heat only kicking on if it hits 60. Except for occasional overnight pit stops in the in-house outhouse, a good down comforter makes anything over 60 unneccesarily warm. Love that dinero-saving, warm comforter.
Hvac guy is due shortly. Its 46 out, set point is asking for74 inside for the unit but its 65 inside and unit isnt running long or turning on offten despite being so far below the set point. Sounds like a problem to me esecpailly with 72 hours below freezing forecast in a few days. The old unti worked fine... ac did not so we replaced both... wondering why not lol,
The tsat is the control point. It brings the outdoor unit on by sending 24 volts up the yellow wire to the compressor contactor. Fan and compressor outside come on. If the temperature is low outside and the temperature continues to drop inside because enough heat cannot be extracted by the heatpump the backup heat should come on. Your furnace upstairs should be on if that's the case. there could be a outdoor tstat on the yellow wire too which locks out the heatpump below a certain temperature. Mine was set at 40. Below that temp only the gas furnace came on because it was a waste to use the heatpump.
Can you hear your compressor running? There's 2 motors out there, a fan and a refrigerant compressor. There should be 2 copper lines. Is the larger line hot?
I dont have a heat pump this is Tx natural gas heater.
Heater keeps kicking off line according to my repair guy so I am resetting it by shutting down power for 2 minutes when it goes off . Its running about 10 or 15 minutes before it kicks off line again. He wil back in the morning to work on it further to see if he can tell what is wrong.
I had a roof replacement is the only thing that changed in the past year since the heater was being run last. He will check the vent on the roof to be sure something is not restricting air flow. I think its doing what it has been which is shutting down. We do not think it had been running until he got here today. So home held mid 60s temp without heater running. But outside temperatures will drop from mid 30s to mid 40s here down lower on sunday. We are up to 67 degrees now so still cold. Im not resetting it over night so will see how much lower it drops by morning when I get up and reset it before he comes over.
Post on Houzz--the Home Forum for HVAC
Have to join to post
Lot of good info there from guys who work in HVAC industry
They likely handle Tranes
There is also a website out there for HVAC service people
They let regular homeowners post questions--
Don't remember that site's name
Some units have some ideocyncratic behaviors and some people might be more familiar if they have solved similar problems
The blocked vent could be issue
But if your older/replaced unit could heat your house to more comfortable temp and this newer one which should be just as capable but more efficient can't -- then the issue is with THAT unit and anything that happened during its installation...
The insulation is not issue, your windows aren't the issue===
Now if the original unit struggled to do what you expect from this new unit then you might be questioning other factors related to comfortable temps inside.
Was the current HVAC unit installed by different company than one replaced?
We use the same plumbers who did the original install in our house (second owners here) but totally different HVAC people...
We had problem with a heat expansion valve not working properly on house we owned prior to this one--it prevented the heater from working properly--
Has your guy checked the heat expansion valve--I think that is what it was called...
In that house we were the original owners, bought from builder, and the HVAC guy found insulation in some of the heating runs which blocked air flow--
Careless construction people when house was built back in early 80s
Maybe something happened when your roof was replaced to cause debris to fall into the vent stacks...
We are also in TX--DFW area--the MidCities between FTW and Dallas
Getting some winter weather so appreciate your predicament
If you have cathedral type ceilings I know those things to be a real pain. Warm air rises. You're heating all that air above you and it's not where you live. I've seen the problem before back in the 80s in a new McMansion. Unit ran all the time. If memory serves me the customer just had the fan on all the time to keep all the air circulating.
The most effiecient way to build a home is a small box shape. In colder climates the smaller the better. Russian homes are always small, do you want the heating bill for a 3000 sq ft house in an arctic enviroment with high ceilings?
I noticed you said it's colder than usual. Maybe there's no allowance for this built in.
Try taking the filter out for awhile and see what happens. If they're dirty they do restrict airflow. If it's been running a lot it will be dirtier too.
He does not have a heat pump--
Did you not read the original post where he said his replaced unit was perfectly capable of heating this area w/o any issues==even in very cold weather...
Yes--higher ceilings are not the best design for efficient HVAC heating but the old unit heated fine
The problem is with the NEW unit's ability to run long enough to cycle enough cold air out and warm air in
I dont have a heat pump this is Tx natural gas heater.
Heater keeps kicking off line according to my repair guy so I am resetting it by shutting down power for 2 minutes when it goes off . Its running about 10 or 15 minutes before it kicks off line again. He wil back in the morning to work on it further to see if he can tell what is wrong.
I had a roof replacement is the only thing that changed in the past year since the heater was being run last. He will check the vent on the roof to be sure something is not restricting air flow. I think its doing what it has been which is shutting down. We do not think it had been running until he got here today. So home held mid 60s temp without heater running. But outside temperatures will drop from mid 30s to mid 40s here down lower on sunday. We are up to 67 degrees now so still cold. Im not resetting it over night so will see how much lower it drops by morning when I get up and reset it before he comes over.
This is a brand new unit, yes? There's only about two or three things that could be causing the problem. You might need a new tech.
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70, during the day? 65, at night? Whoa Nellie! 
