bob,buck, imerc, pino, others, hvac ?
Hey guys got a real construction question this time can you help? I need to know if the return side of a heat pump needs to be claculated the same as the supply side. If I use insulated flex duct for the return does it matter how straight the run is. I know the supply side needs to be as straight as possible, what about the return? Also talked wife out of replacing unit so I could use funds on other projects, moneys all gone and winters here and still only half done. Last night was the coldest yet and heat pump froze up, Ice all over the cooling fins. Now unit does not seem to be putting out much heat, its been running for about 14 hours non-stop house is still only luke warm (wife wearing mittens and scarf and scowling at me) Can I fix this? or am I going to have to admit that I am an idiot?
Replies
Can I fix this? or am I going to have to admit that I am an idiot?
Don't bother admitting it. Your wife will let you know.
;)
the return ducting should be as large or larger than the supply. bends do reduce flow. We don't use much hot air ducting here but they usually lay it out so the returns are shorter and closer to the plenum and same size or larger.
Excellence is its own reward!
until someone with more specific experience weighs in, here's my thoughts from working with much smaller, much higher pressure pneumatic systems- return or vent lines usually need to be even bigger to move the same volume of air because they operate at a lower pressure- otherwise it creates a back pressure strain on the positive side of the circuit. figure in any friction increasing factors (corrugated ducts, elbows, etc) on top of that. a pro can tell you by how much for your system's particulars.
m
There may be a problem with the defrost control on your heat pump condensing unit if that is the coil that is freezing up. Do you have an electric "emergency" resistance heat coil? You might be able to run on electric heat only if the heat pump is not doing the job. How old/what brand is the unit? Where are you located?
Edited 1/4/2004 4:15:45 PM ET by SteveL
thanks all,
It is a 3.5 ton Goetl, its about 1000 years old. I spoke with an engineer at Goetl and he said that the model was discontinued be fore he started working there, 19 years ago. I know I need to upgrade, especially since I just added two new rooms (750 sqft)But you know how some projects can go a little over budget, well this one went a lot over budget. I would really like to hold the unit together at least untill spring, hopefully I can save up some $ to get a new one then. Been up for about 2 days trying to get insulation in and now rockin the walls, man the mud is everywhere, now it is on my keyboard.
Ditto Piffen and SteveL
Who ever invented work didn't know how to fish....
If the compressor coils are still ice-bound, you won't get any useful heat. There should be an auto-defrost. If not, or it isn't working, use a heat gun or hair dryer to make sure there isn't ice in all the nooks and crannies. Don't know if older units had the defrost thing. Heat pumps will also not deliver any heat when the outside air temperature is too low. The colder it is, the less heat there is to extract from the outside air. Below 20 or so, it should switch to emergency resistive heating. Don't know if the defrost is resistive heater or if it just switches to AC mode for a while to heat up coils. Post the make and model of the system and somebody can tell you better.
'wife wearing mittens and scarf and scowling at me' Buy a whole bunch of candles and put them all over the bedroom. It will warm her heart and earn you some temporary brownie points. Hey it cant hurt! Just be sure to tell her that you know this is a temporary fix until you can aford some bigger candles,.. I mean new heating system.
Can't hurt huh?
"During 1999, an estimated 15,040 home fires started by candles were reported to public fire departments. These fires resulted in an estimated 102 civilian deaths, 1,473 civilian injuries and an estimated direct property loss of $278 million.
Candle fires accounted for an estimated 4.1% of all reported home fires.
Two-fifths (40%) of the home candle fires started in the bedroom."
from: http://www.nfpa.org/Research/NFPAFactSheets/CandleSafety/CandleSafety.asp
Boy you are a kill joy. You can place candles inside of glass holders or get the kind that float in water. Just make sure they are not within striking distance of the bed.
Probably what SteveL said. I had this a few years ago with a particularly cold winter - the H.P. seemed to run constantly. I passes it off as just the extremely cold weather. Until I got a whopping power bill - maybe $150 more than my normal winter bill ! Turns out the compressor was shot and the unit had been cooking on the electric heat strips 24/7.
Hope this ain't it, but you'd better check it quick. If the meter base is making that little whirring sound, and you can't see the little wheel in the meter, you're in trouble !
Greg.
Actually my bill was huge, I assumed it was due to the added space heaters in the new rooms. How would I check to see if the compressor is shot, and is it something I can replace or is the unit beyond help? Thanks for the advice
Hey, I don't really know - I just called my usual service guy !
I hope that's NOT what you're dealing with - you'll have to decide between a $1000 repair or to replace the unit, which, from what you've said about the age, would be the better option. New units are much more efficient - your power bill may drop $40 or $50.
Greg.
Sheesh, give it a rest will ya, I appreciated the suggestion and despite your comments, plan to try it tonight. Considering the fact that I have survived this long, I think I can manage a candle. Oops, I guess that last statement was not logical since all the idiots that died had survived until that fatefull candle incident. What I mean to say is that idiots abound, considering how many there are around I'm surprised there are not more candle fatalities. But I promise, no candle will kill me. (admittedly that promise sounds disturbingly similar to the famous last words of a redneck, "Hey ya'll, Watch this") but I do thank you for your concern, and I thank reinvent for the suggestion.
Ps before you rednecks flame me, I am from the heart of Dixie so when you criticize don't accuse me of bein a damn yankee.
Edited 1/8/2004 12:40:29 PM ET by constructioergosum