hueyville
01-21-2010, 06:09 PM
Folks,
This is my first post here so if I am breaking any site code of conduct let me know. I am not a full time HVAC technician. What I mostly do is preventive maintenance and inspections. I have my EPA Universal license and through Mainstream I have my Indoor Air Quality, Preventative Maintenance Tech and Green HVAC/R certifications.
Mostly I check systems for acid, mold, and obvious problems. I add U.V. lights, upgrade filtration units, swap out damaged heat strips, etc. I leave the big work and real service work to the folks that are factory approved for the applicable units.
I have installed quite a few HVAC units in the past but as I have gotten older and damaged my back I have had to stop doing the really physical stuff and restructured my business to something an old man can do. Indoor Air Quality and Energy efficiency are my specialties now along with a little PM work.
Now onto the subject at hand. I have a client with a retrofitted Trane heat pump model XL19i (2TWZ9). They called me on a Friday night during the recent cold spell we had here in north Georgia because there system was not heating the house and the company that installed it told them it would be three days to get a tech there due to a back log of service calls.
The temps were going down into the low teens at night, never getting out of the twenties during the day and since i felt sorry for their dog who is old like me, I decided to go look and see if it was something simple.
The breaker on the strip heaters had tripped. Since I didn't know what had caused it I did a little checking before resetting it. The contactors/relays were good and so were the strip heaters themselves. Since we had just gone through some icing I assumed that we had a brownout while they were under load which kicked the breaker. I did see that both strip heaters had 14.0 ohms of resistance and 237 volts of supply. I measured this using both a Fluke 87 V and a Fluke 189 so my values should have been within .025 to .050%.
This told me they had a total of about 8,000 watts of resistive heat and my chart said for their 3,000 sq. ft. home they should have around 12,000 total watts of supplemental heat. At that point I wondered if the breaker kicked due to the strip heat being run too much but with a 60 amp breaker and the wiring in place, that should not have been an issue. I reset the breaker and babysat the unit for a half hour to make sure I wasn't going to burn down the house.
I left, charged them a fair price and told them they needed to look at having their strip heat upgraded before we had another really cold spell. Last week they got their electric bill and it was 650.00 dollars and they freaked. I told them that it could have something to do with the fact we had just gone through the coldest two weeks since 1986 or there could be an additional problem with the heat pump. I advised them to call the a factory authorized Trane service company.
They called the original installer who came out and said nothing was wrong and gave them a bill for a service call. Even said not to worry about the strip heat. It don't get that cold, that often.
They have been watching their thermostat (Trane XT500c) and have noticed that every time the unit comes on it lights up saying the emergency heat is on. It stays on for a couple of minutes (their words) they say and then goes off. With the warmer temps we are now having I decided that might not be normal so went to look. (gotta take care of good clients)
Day before yesterday I opened the heat pump to find a trouble code. Decoded it to indicate "two unanswered timeouts on defrost". I checked the pressures, reversing valve and expansion valve and all seemed o.k. I watched the system go through a couple of cycles and everything appeared normal by my standards except that every time the unit cycles on, the heat strips come on for 30 seconds to a minute then shut off and then the unit operates as it should by my limited knowledge. I reset the machine to make the loud tick-tock and trouble lights flashing go away.
Whoever installed the unit took the service manual and didn't leave and owners manual for anything. So I went back today and no trouble codes but the heat strips still come on for a half a minute every time the units comes on. This just doesn't seem right. That is a lot of electricity to burn for a unit rated at 19 SEER. I am suspecting a problem with the defrost board but that is a guess.
Anyone want to throw me a clue? I will buy the coffee next time... The client is concerned about their electric bill and I think there is an issue but the factory service folk said it was all working correct. The trouble code was definitely present and it just don't make sense to me. Not being Trane authorized puts me in a bad position. Nobody wants to tell me much and the factory guy said nothing was wrong. I don't want my client getting another astronomical electric bill. All help and advice will be considered for educational purposes only.
Thanx,
Michael
This is my first post here so if I am breaking any site code of conduct let me know. I am not a full time HVAC technician. What I mostly do is preventive maintenance and inspections. I have my EPA Universal license and through Mainstream I have my Indoor Air Quality, Preventative Maintenance Tech and Green HVAC/R certifications.
Mostly I check systems for acid, mold, and obvious problems. I add U.V. lights, upgrade filtration units, swap out damaged heat strips, etc. I leave the big work and real service work to the folks that are factory approved for the applicable units.
I have installed quite a few HVAC units in the past but as I have gotten older and damaged my back I have had to stop doing the really physical stuff and restructured my business to something an old man can do. Indoor Air Quality and Energy efficiency are my specialties now along with a little PM work.
Now onto the subject at hand. I have a client with a retrofitted Trane heat pump model XL19i (2TWZ9). They called me on a Friday night during the recent cold spell we had here in north Georgia because there system was not heating the house and the company that installed it told them it would be three days to get a tech there due to a back log of service calls.
The temps were going down into the low teens at night, never getting out of the twenties during the day and since i felt sorry for their dog who is old like me, I decided to go look and see if it was something simple.
The breaker on the strip heaters had tripped. Since I didn't know what had caused it I did a little checking before resetting it. The contactors/relays were good and so were the strip heaters themselves. Since we had just gone through some icing I assumed that we had a brownout while they were under load which kicked the breaker. I did see that both strip heaters had 14.0 ohms of resistance and 237 volts of supply. I measured this using both a Fluke 87 V and a Fluke 189 so my values should have been within .025 to .050%.
This told me they had a total of about 8,000 watts of resistive heat and my chart said for their 3,000 sq. ft. home they should have around 12,000 total watts of supplemental heat. At that point I wondered if the breaker kicked due to the strip heat being run too much but with a 60 amp breaker and the wiring in place, that should not have been an issue. I reset the breaker and babysat the unit for a half hour to make sure I wasn't going to burn down the house.
I left, charged them a fair price and told them they needed to look at having their strip heat upgraded before we had another really cold spell. Last week they got their electric bill and it was 650.00 dollars and they freaked. I told them that it could have something to do with the fact we had just gone through the coldest two weeks since 1986 or there could be an additional problem with the heat pump. I advised them to call the a factory authorized Trane service company.
They called the original installer who came out and said nothing was wrong and gave them a bill for a service call. Even said not to worry about the strip heat. It don't get that cold, that often.
They have been watching their thermostat (Trane XT500c) and have noticed that every time the unit comes on it lights up saying the emergency heat is on. It stays on for a couple of minutes (their words) they say and then goes off. With the warmer temps we are now having I decided that might not be normal so went to look. (gotta take care of good clients)
Day before yesterday I opened the heat pump to find a trouble code. Decoded it to indicate "two unanswered timeouts on defrost". I checked the pressures, reversing valve and expansion valve and all seemed o.k. I watched the system go through a couple of cycles and everything appeared normal by my standards except that every time the unit cycles on, the heat strips come on for 30 seconds to a minute then shut off and then the unit operates as it should by my limited knowledge. I reset the machine to make the loud tick-tock and trouble lights flashing go away.
Whoever installed the unit took the service manual and didn't leave and owners manual for anything. So I went back today and no trouble codes but the heat strips still come on for a half a minute every time the units comes on. This just doesn't seem right. That is a lot of electricity to burn for a unit rated at 19 SEER. I am suspecting a problem with the defrost board but that is a guess.
Anyone want to throw me a clue? I will buy the coffee next time... The client is concerned about their electric bill and I think there is an issue but the factory service folk said it was all working correct. The trouble code was definitely present and it just don't make sense to me. Not being Trane authorized puts me in a bad position. Nobody wants to tell me much and the factory guy said nothing was wrong. I don't want my client getting another astronomical electric bill. All help and advice will be considered for educational purposes only.
Thanx,
Michael