Furnace efficiency

1947 Views 19 Replies 6 Participants Last post by jagans, Dec 15, 2012

marriedmanw

Discussion Starter · Dec 12, 2012

I have a Carrier Gas Furance. The Model is 58WAV111-13112. Is this an over 90% efficiency gas furance??

I have done several searches and can't find answer. The thermostat I have has different setting for furances over 90% efficiency.

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HVAC1000

· #2 · Dec 12, 2012

Answer

Alright. So there are a few ways to find out. The easiest is to look at the furnace itself. If there is a white PVC pipe coming out of it to vent it you have a 90+ percenter. If it is shiny galvanized metal you have yourself an 80%. The next way which is actually more informative is to check the serial number (also labled as S/N inside furnace cabinet). It can tell you the date it was made, percent efficiency, and how many BTU your unit is. If you wanted to post it i can decode it for you.

marriedmanw

Discussion Starter · #3 · Dec 12, 2012

HVAC1000 said:
Alright. So there are a few ways to find out. The easiest is to look at the furnace itself. If there is a white PVC pipe coming out of it to vent it you have a 90+ percenter. If it is shiny galvanized metal you have yourself an 80%. The next way which is actually more informative is to check the serial number (also labled as S/N inside furnace cabinet). It can tell you the date it was made, percent efficiency, and how many BTU your unit is. If you wanted to post it i can decode it for you.

Thanks for the help. The furance has the shiney metal piping and I did find a schmetic showing it was 80%.

Before I place a service call again I'll run this problem by the thread. Last night the outside temp was mid 30's and I heat with fireplace. This morning at 6am the fire was out and the upstairs temp was 62. Temp was 74 went I went to bed. I closed the flue and turned on the furance and the setpoint is 67. The furance has cycled 7 times and the temp upstairs is 63. I recently had a service call going into winter and a tune up was performed. Since the unit is only 2 years old we have it serviced in fall and spring. When calling for heat the gas is firing but running short cycles.

I have a Honeywell TH5220 non prog thermostat.

techpappy

· #4 · Dec 12, 2012

What do you mean by upstairs...main floor or 2nd floor. Where is TT located and what is temp at that location. Short cycling can be due to several reasons. Faulty fan motor, fan/limit controls, only 2 yrs old means electronic control board..any codes flashing if so what are they..should be code list somewhere on furnace...could be plugged filter/AC Coil...Was furnace working OK in past?...What's the history...Did you observe the furnace operation during the short cycling..did the main burner(s) actually fire up? More info required.

marriedmanw

Discussion Starter · #5 · Dec 12, 2012

techpappy said:
What do you mean by upstairs...main floor or 2nd floor. Where is TT located and what is temp at that location. Short cycling can be due to several reasons. Faulty fan motor, fan/limit controls, only 2 yrs old means electronic control board..any codes flashing if so what are they..should be code list somewhere on furnace...could be plugged filter/AC Coil...Was furnace working OK in past?...What's the history...Did you observe the furnace operation during the short cycling..did the main burner(s) actually fire up? More info required.

Yes, the thermostat is located on the main floor (ranch house with basement). I keep thermostat set to 67 degrees, and this morning it was 62 degrees upstairs when the fireplace was out. I did not turn on furance till fire is out and flue closed.

We purchased house in September this year, and I called same company that serviced my old house to check out system. The furance cycles more than I thought it should but I figured the outside temp was still mild. Now that it's colder at night it still short cycling. The fan turns on, burners light, then blows heat for about 5 min, fan turns off but before system shuts down the burners reignite and same thing happens. Furance lite the burners 7 times this morning and the furance fan never turned off. The temp in the hallway was 63 degrees after system ran for 1 hour so it only raised temp by 1 degree.

I did check the terminal screws were tight at thermostat, I keep filters replaced regularly, and I removed the flame sensor cleaned with steel wool and reinstalled. According to the serial number the furance and AC was installed in 2010, so I contacted company that installed (stamped on thermostat) since I found out the parts are under warrenty. I still have to pay service call and labor.

I have replaced some things before but felt this was out of my comfort level. Tech at the house now. I will post what they find. Kind of bummed that I paid $120 in September for cleaning and tune-up and was told system is in proper order.

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marriedmanw

Discussion Starter · #6 · Dec 12, 2012

Technician stated that the gassure pressure was reading to high (3.95"wc and he adjusted down to 3.5"wc) which was causing high limit switch to trip. Also noted that the exchange is at the minimal size and recommended changing the filters every 30 days. I always use the nice pleated filters, but will go back to the blue mesh looking filter. Hopefully my natural gas bill will be lower next month.

HVAC1000

· #7 · Dec 12, 2012

marriedmanw said:
Technician stated that the gassure pressure was reading to high (3.95"wc and he adjusted down to 3.5"wc) which was causing high limit switch to trip. Also noted that the exchange is at the minimal size and recommended changing the filters every 30 days. I always use the nice pleated filters, but will go back to the blue mesh looking filter. Hopefully my natural gas bill will be lower next month.

This sounds like the flame sensor. If it continues happening you may want to check how good the grounded connection to the furnace is. The flame sensor relies on a good ground connection. Also check the whole house ground. If it was not grounded properly when built the connection can go away over time and not work. Even if it has worked in the past

beenthere

· #8 · Dec 12, 2012

Sounds like low air flow tripping the high limit.

May want to have another return added.

marriedmanw

Discussion Starter · #9 · Dec 13, 2012

beenthere said:
Sounds like low air flow tripping the high limit.

May want to have another return added.

Thanks for the suggestion. I will talk with HVAC company to see how much that would be. Should they recommend installing near current return vent or place a couple feet away? The current return opening is 1' x 2' roughly and does a 90 down then another 90 into the furance. The return is on the main floor and has a little over 8' in total duct work for the return. The furance is in the basement and the return prettly much sits over the furance on the main level.

Thanks

beenthere

· #10 · Dec 13, 2012

Can be near the current one, or placed somewhere else on the first floor. Would be nice to have it on the second floor for cooling season, but doesn't have to be.

marriedmanw

Discussion Starter · #11 · Dec 14, 2012

beenthere said:
Can be near the current one, or placed somewhere else on the first floor. Would be nice to have it on the second floor for cooling season, but doesn't have to be.

I was thinking about putting one on the basement level but not sure where it could be convenient. The furnace is in the garage but we use it for storage instead of car parking. Could it just be as easy and cutting hole in return and putting a vent cover over hole? Could I connect to the return and put vent between the floor joist? I have taken a picture of my furance and return.

Thanks for help this far. I'm surprise that the HVAC tech did not suggest a second return yesterday. He did say the current return is bare mininum.

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beenthere

· #12 · Dec 14, 2012

Basement is not a good place per say with your furnace. Since it uses the basement air for combustion. A return in the basement would probably cause a back draft in the flue, and could pull CO into the house.

You could just cut another return on the first floor and connect it to the existing return drop.

NiNe O

· #13 · Dec 14, 2012

I'd put a return in the befrooms, all of them.

marriedmanw

Discussion Starter · #14 · Dec 14, 2012

beenthere said:
Basement is not a good place per say with your furnace. Since it uses the basement air for combustion. A return in the basement would probably cause a back draft in the flue, and could pull CO into the house.

You could just cut another return on the first floor and connect it to the existing return drop.

I think if I added a return to the finished living space in the basement it would be about 17 ft with two 90 degree angles. That way it would not pull air from the garage. I would consult with the company that installed the furnace to not cause any warrenty or performance issues.

One last question, then I believe I'll be informed on this issue. For a second return either in the finished living space in the basement or on the main floor what size duct would be reasonable?

beenthere

· #15 · Dec 14, 2012

For the basement,. you would be limited by the size of the supplies you have in that finished area. So how much air does the finished basement get. Might be able to use as big as an 8".

First floor can be much bigger. So the question is how short on return are you. might be able to use as small as a 12" for the first floor.

jagans

· #16 · Dec 14, 2012

This is of another matter, but I see another flue pipe coming into the furnace flue is that from a gas hot water heater tank? Isnt that a NO NO. Also, having Gasoline cans in a space where there is open flame is INSANE, especially with a water heater. Gasoline fumes will crawl across the floor and WOOF, YOU AND YOUR FAMILY ARE TOAST. Cmon man you know this dont you????

beenthere

· #17 · Dec 14, 2012

Code permits a water heater and furnace to be vented together.

marriedmanw

Discussion Starter · #18 · Dec 15, 2012

jagans said:
This is of another matter, but I see another flue pipe coming into the furnace flue is that from a gas hot water heater tank? Isnt that a NO NO. Also, having Gasoline cans in a space where there is open flame is INSANE, especially with a water heater. Gasoline fumes will crawl across the floor and WOOF, YOU AND YOUR FAMILY ARE TOAST. Cmon man you know this dont you????

Yes the furnace and water heater are vented through the same pipe which I believe is OK by code since both were professionally installed. As BeenThere also mentioned it is OK by code.

I appreciate your concern but both gas cans are empty. I left them at my work bench since I'm making the non-vented cans into vented ones.

marriedmanw

Discussion Starter · #19 · Dec 15, 2012

beenthere said:
For the basement,. you would be limited by the size of the supplies you have in that finished area. So how much air does the finished basement get. Might be able to use as big as an 8".

First floor can be much bigger. So the question is how short on return are you. might be able to use as small as a 12" for the first floor.

Thanks for your assistance and explanation. After the holidays I will have HVAC company come out and see if they can do a cfm test at the return, then look at what they suggest for secondary return. At least now with the suggestions from this thread I feel that I have a better understanding of the work that needs to be completed. :thumbsup:

jagans

· #20 · Dec 15, 2012

80% Found the manual on the web, but its too big and exceeds the ridiculous 100kb limit set by this site. PM me your email and Ill send it on.

Peace, JimA

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