I have a Trane XL15i

[David Honeycutt]

I also have a Trane XL15i, with electric strip heaters as my auxiliary heat. When it gets particulary cold, say less than 20 F, my thermostat shows that my auxiliary heat is supplementing, but I have my doubts. The system is not keeping up, with my inside temp dropping as soon as the auxiliary heat kicks on. I've measured my register temps when this happens, and it is reading 65 to 70 F. If I engage my emergency heat, meaning the heat pump is turned off and only strip heaters engaged, my house warms up within 20 minutes; however, I have to do this manually. My contractor says that he thinks the heat pump is getting stuck in defrost mode, so the strip heaters are being negated by the A/C during defrost mode. He's planning on installing an outside temp sensor to force the heat pump "off" when the temp gets below a certain level. Why is this necessary if the system is operating correctly? Why would my system be in a prolonged defrost mode? I've also noticed a massive of ice pooling around the base of my heat pump. Any assistance would be greatly appreciated.

[beenthere]

Made this its own thread. You are not permitted to post in other peoples threads in the AOP forums. Please read our site rules, thank you.

[beenthere]

Sounds like your contractor doesn't know how to diagnose the problem. So he is going to band aid it and cause you a high heating bill.

Possible not all of your aux is coming on like it should. Which could be a wiring issue.

[wahoo]

You need to hire a competent service technician. You've evidently not found one yet!

[David Honeycutt]

I apologize for the site rules confusion. Won't do it again.

[dan sw fl]

"... Massive ice pooling .. " = Significant Defrost issue.!

Location.?
Less than 35'F and humid area will create ICE on the condenser

Close to lake or river?

[catmanacman]

i would not want my heat pump turned off when its cold outside .next time it is doing it ,go to the unit and find the big insulated line and see if it is hot or cold ,you will need to move the insulation unless there is a bare spot can be either inside or outside

[duckman06]

I also have a Trane XL15i, with electric strip heaters as my auxiliary heat. When it gets particulary cold, say less than 20 F, my thermostat shows that my auxiliary heat is supplementing, but I have my doubts. The system is not keeping up, with my inside temp dropping as soon as the auxiliary heat kicks on. I've measured my register temps when this happens, and it is reading 65 to 70 F. If I engage my emergency heat, meaning the heat pump is turned off and only strip heaters engaged, my house warms up within 20 minutes; however, I have to do this manually. My contractor says that he thinks the heat pump is getting stuck in defrost mode, so the strip heaters are being negated by the A/C during defrost mode. He's planning on installing an outside temp sensor to force the heat pump "off" when the temp gets below a certain level. Why is this necessary if the system is operating correctly? Why would my system be in a prolonged defrost mode? I've also noticed a massive of ice pooling around the base of my heat pump. Any assistance would be greatly appreciated.

Please give us more info on your home. What size home to you have? What size is your heat pump?

It could be as simple as a wiring problem as Beenthere pointed out or something more in depth. I have installed 100's of Trane XL15 heat pumps and never look out heat pump.

In my area there is no need. While I have the XR15 in my home which is the same basic systems as Xl15. It all about how it was sized and wired with heat pumps. While other things factor into the correct operation I see these 2 things being the most common issues in my area.

A remote sensor outside is not a bad thing but if installer is just adding one because he can't figure out anything else that is the wrong thing to do. The reason you want the heat pump in your home is for energy efficiently compaired to the emergency heat (heat strips) which are very high costed way to heat your home.

I would call the installing dealer and ask for their senior tech to come out and review over the system to ensure all the bases have been covered.

[David Honeycutt]

Temperatures have been hovering between 10 and 25 degree for last couple of weeks. Not near a lake or river. The condenser is beginning to ice pretty thoroughly. I have yet to see the condenser go through a defrost cycle.

[David Honeycutt]

The large copper line is hot during operation. I measured it at about 120 F last night, when the outside temp was around 15 F or so. The 120 F was measured right before it entered the air handler.

[David Honeycutt]

My heat pump is a 5 ton XL15i. The system includes a variable speed air-tite air handler, with 25 KW of electric strip heating for back up. My house is approximately 3500 square feet, two stories, with a dual zone system controlled by Honeywell controllers and thermostats. My house is in construction, with the upstairs being completed, and the downstairs fully insulated, and about half of the downstairs drywalled. Wall insulation is approximately R30, and attic insulation varies from R50 in vaulted areas, to R80 in other areas. I live in a very rural area, so there are no "senior technicians", just the contractor himself. So far, he seems a reasonable fellow. I'm just trying to educate myself so I can have an intelligent conversation about what is going on, and if necessary, point him in the right direction. Thanks for any asistance.

[dan sw fl]

My heat pump is a 5 ton XL15i. The system includes a variable speed air-tite air handler, with 25 KW of electric strip heating for back up.

My house is approximately 3500 square feet, two stories, with a dual zone system controlled by Honeywell controllers and thermostats.

Wall insulation is approximately R30, and
attic insulation varies from R50 in vaulted areas, to R80 in other areas. .

How do you achieve R30 in the walls?

25 kW = 85,300 BTU /Hr ... I hope that it's staged in 5 * 5 kW arrangement.
25,000 watts
3.412 conversion factor
85,300 BTU/Hr

[dan sw fl]

My heat pump is a 5 ton XL15i. The system includes a variable speed air-tite air handler, with 25 KW of electric strip heating for back up. My house is approximately 3500 square feet, two stories, with a dual zone system controlled by Honeywell controllers and thermostats. My house is in construction, with the upstairs being completed, and the downstairs fully insulated, and about half of the downstairs drywalled. Wall insulation is approximately R30, and attic insulation varies from R50 in vaulted areas, to R80 in other areas. I live in a very rural area, so there are no "senior technicians", just the contractor himself. So far, he seems a reasonable fellow. I'm just trying to educate myself so I can have an intelligent conversation about what is going on, and if necessary, point him in the right direction. Thanks for any assistance.

Rural area ... Do you know what town is close to you?

Or is that a secret?

How many windows?
What type?

Total window area =~ 400 sq feet?

[David Honeycutt]

R30 in walls achieved with standard R21 in wall cavities, and 1-1/2" polyiso on exterior walls (~R10). Staging of strip heaters is unknown to me, but they are also Trane equipment, integrated with the air handler.

[David Honeycutt]

Closest town is Spokane, about 90 miles away. With respect to windows, I don't have that data handy, but I would guess about 500 square feet. Most are double paned, argon filled, with low-E coating. Some are triple paned, argon filled, with low-E coating. They were all included in my manual J calcs. I believe my heat loss came up to about 69K BTUH.

[dan sw fl]

41,000 BTU/hr heat loss at 0'F
Basis:

1,600 Sq. Ft Ceiling R-50
2,800 Sq. Ft Walls R-30
400 Sq. Ft Windows U 0.4
Infiltration 0.4 ACH on 28,000 feet^3

6,000 Heating Degree Days
84,000,000 BTU heat loss per year / 92% efficiency
900 therms Natural Gas

~$ 875 annual electric for heat pump at C.O.P.of 2.8 and $0.10/ kwHr


I don't have XL15i spec in front of me to determine a thermal balance point (might be low to mid 20's F).

O.A.
30'F Heat Loss = 23,430 BTU/Hr
25'F Heat Loss = 26,360 BTU/Hr
20'F Heat Loss = 29,290 BTU/ hr


41000 70 585.7142
50 20 29285.

45 25 26357.

40 30 23428.

[dan sw fl]

Spokane Temperature Jan Feb Mar xxx_ Apr May Jun yyy_ Jul Aug Sep zzz_ Oct Nov Dec 00 Annual
Avg. Temperature ___ 27.1 33.3 38.7 xx 45.9 53.9 62.0 yy 68.8 68.4 58.9 zz 47.3 35.1 27.8 00 47.3
Avg. Max Temperature 33.2 40.6 47.7 xx 57.0 65.8 74.7 yy 83.1 82.5 72.0 zz 58.6 41.4 33.8 00 57.5
Avg. Min Temperature 20.8 25.9 29.6 xx 34.7 41.9 49.2 yy 54.4 54.3 45.8 zz 36.0 28.8 21.7 00 36.9

Days with Max Temp of 90 F or Higher 0.0 0.0 0.0 < 0.5 < 0.5 2.0 9.0 7.0 1.0 0.0 0.0 0.0 19.0
Days with Min Temp Below Freezing 26.0 22.0 21.0 10.0 2.0 0.0 0.0 0.0 1.0 9.0 20.0 27.0 138

Spokane Heating and Cooling
___________________Jan Feb Mar xx Apr May Jun yy Jul Aug Sep zz Oct Nov Dec 00 Annual
Heating Degree Days 1175 888 815 xx 573 344 139 yy 30.0 56.0 223 zz 549 897 1153 00 6842
Cooling Degree Days 0.0 0.0 0.0 xx x 0.0 0.0 49.0 yyy 148 161 40.0 _zzz 0.0 0.0 0.0 00 398