Best Rated threads in HVAC Discussionsshow all threads

Subject Author Posted Replies
 
Trane XL 80 not turning on
The unit (model: TXC037C4HPC0, serial: R435RF05G, mfg: 10/2000) was working well (over the last few years it was used primarily for the air conditioning function) until we got 16 inches of water in...
1 year ago
 
Rheem heat pump defrost cycle question
My question is about the sequence of operation during the defrost cycle. I am an electronics technician with an engineering background. The air handler is an RH1T4821STANJA, outdoor cube is an...
4 years ago 2
 
Carrier vs Comfortmaker
I've gotten 3 quotes for a new central 5 ton A/C unit here in central Flori da. My last Trane unit lasted 12 years, so I thought why not get another. But 2 companies said they would recommend a...
5 years ago 5
 
carrier 58sxx100 furnace has no spark or gas to the pilot on start up sequence
The gas furnace is a Carrier 58sx100-cc-1. On start up it has no spark to the pilot (3 wire). There is no gas from the gas valve going to the pilot. So it never fires up. Pressure switch closes when...
5 years ago 1
 
Furnace Limit sensor (Therm-o-disc type) question
My furnace has both the Fan Limit switch control where I set the pointers, and a secondary limit sensor which is the Therm-o-disc type. I recentle replaced the fan limit control because the fan ran...
6 years ago 5
 
Carrier Infinity Thermostat - does not resume after power failure
I have a Carrier Infinity system. In general, it works great. But whenever there is a power failure (t-storms), the thermostat waits for someone to confirm the type of air filter and other...
9 years ago 2
 
Flame sensor - please help
I have a Carrier 58MCA that is not working. I replaced the flame sensor last December and it was fine all winter. Now it's cold again and I have no heat. The board again flashes 34 after it lights...
11 years ago 6
 
Johnson Controsl M15 -> M35
I'm having some trouble with the Johnson Controls Vent Damper (M15AB-2) on my furnace. Unfortunately, this model is outdated and no longer available. The currently available model is M35. Can...
12 years ago
 
gas furnace OK on a GFI circuit?
In brief, is it OK for a gas furnace to run off a GFI circuit? We have a gas furnace that's about 20 years old in the basement. (It also has a more recent central A/C unit coil on it.) The furnace...
13 years ago 15
 
Only 1/3 evaporator coil is cold
Just moved my 2.5 ton split unit upstairs, and only the bottom third of the evap. coil is cold. Would this implicate too little refrigerent? Any other ideas? Thanks for your advice! DK How did you...
13 years ago 15
 
Furnace will only run one cycle then stops
Hi All, Our furnace is a Bryant 90 High Efficiency (power vent) and it is about 18 years old. When the furnace is switched off then on (from either the power switch or thermastat) it will run one...
13 years ago 17
 
How to determine return air duct size for a 50,000 BTU Gas Furnace
Hi, Folks, I am trying to install the 50000 BTU Weather King gas furnace on my rear house. Before, there were only space heaters in that house, so I have to "design" the ductworks and install the...
14 years ago 14
 
Geothermal system and sinkholes
When I had my home built 8 years ago, I installed a geothermal heating/ cooling system. It is a vertical system with 3 wells although I am unsure which are supply and which are return wells. I have...
11 years ago 5
 
ignition transformer wiring
Which of these two statements are true- When wiring the secondary of a 15kv (.25A) transformer you should ground one side of the centre tapped transformer to earth if it is not used, as the ignition...
12 years ago 8
 
Should my condensor fan run when heat is on?
Real basic question I think about HVAC. I replaced my thermostat on our HVAC system the other day and when i kicked on the heat, it turned on the fan that's in the condensor outside (that big...
12 years ago 18
 
Boiler Flange, Gasket or sealant?
I have an oil-fired boiler for heating my home. This one is welded steel. There is a large flange (about 9" in diameter & secured by 6 bolts) where the controls & immersion coil go into the water...
12 years ago 15
 
Brown liquid from flue pipe
I have a house with an asbestos flue. The water heater and gas furnace have regular sheet metal flue duct, then up in the ceiling the metal flue slips into this ceramic/asbestos flue - 6" diameter....
13 years ago 13
 
Advantage of Azeotropes?
I can figure out what azeotropic refrigerants are, but not why. What's the advantage? Or is is just a way to get the boiling point of non-CFCs to match the older CFC single-component refrigerants?...
13 years ago 5
 
Can't work on AC in the rain?!?!
I have 2 Trane units that are not working right. Called the local Trane high end dealer about a week ago and made an appointment. I work about an hour away from home so took the day off today to meet...
13 years ago 19
 
Is a refrigerant leak around the Schrader valve "normal"?
Inside heat pump evaporator coils freezing up. Tech came out said unit low on refrigerant and added 1 1/2 pounds. Worked a day and a half started freezing up again. Called same company, same tech came...
5 years ago 10