Need Some HVAC-R Help. (for home)

[Jsvob03]

So, this past spring i had a new heat pump/furnace put in. It's been nothing short of amazing. bills are WAY lower thus far compared to last year at this time. hell, keeping the house @ 72* all sumer cost at most 35 / month! (1700sq ft house).

anyhow, now that its cold, it makes this rather odd noise. It sounds like a damn dinosaur is roaring in my side yard! My only guess is that when the system goes into defrost mode, it has to switch directions of flow, which means pressures need to equalize before it can happen. is the noise an internal pressure release (obviously can't vent to the atmosphere)?

the noise will happen, and then 30 minutes later happens again. but then its gone for a while. this is why i believe it to be defrost as well, because the defrost cycle will run for 30/60/90 min, depending on setup.

[jporter12]

Does it only do it when it's really cold out, such as morning, or night? If so, it might just be too cold for it. Beyond that, it sounds like it should still be under warranty, and I would be having it checked out, maybe the refrigerent charge is too high or something. I really don't know about the ins and outs of a heat pump system, but I do know some about standard heating and A/C, and the heat pump is essentially the A/C working in reverse, but not quite as simple, due to needing to defrost, etc....

[spz9]

+1 guess for defrost mode.

my dinosaur is in the back yard and it was pretty loud till i replaced the caps (it's an old system).

[MattKatz]

It's the reversing Valve shifting for the Defrost mode as you have stated.

Look at your outdoor fan when you hear this...It wont be running.

This is an easy way to tell if its in Defrost....And if it looks like its on eFIre with Steam.

In other words....Perfectly normal.

And I do do this for a living...so this is not my opinion.

[serpentracer]

I can't believe you got the heat pump junk. you'll freeze in the really cold winter. that's why I got rid of mine.

I went with a High Efficiency gas furnace. it's 94% efficient. I keep my place at around 70-73 and my highest bill in january for the gas was $60. and I also have a high efficiency gas water heater.

with a heat pump the colder it is, the less efficient they are and they'll run almost non stop in sub freezing temps.

Edited November 6, 2009 by serpentracer

[MattKatz]

Newer Heat Pumps Rock.....I have seen output temps that rival High efficient NAt. Gas Furnaces. And although they do run a lot....No more than your Gas Furnace runs if you really break it down. Both have their pros and cons, but if you go with a HEat Pump with a natural gas backup....Now your talking about the best of both worlds.

[jporter12]

I can't believe you got the heat pump junk. you'll freeze in the really cold winter. that's why I got rid of mine.

I went with a High Efficiency gas furnace. it's 94% efficient. I keep my place at around 70-73 and my highest bill in january for the gas was $60. and I also have a high efficiency gas water heater.

with a heat pump the colder it is, the less efficient they are and they'll run almost non stop in sub freezing temps.

That's why below a certain temp (I don't remember off the top) it's better to switch back to conventional heat. Each year, the newer models become better and better though, and that temp may be lower than before, as I'm sure the efficiency of the newer ones has improved quite a bit. Back in the day an 80% efficient furnace was "good" and today it's 90+, with I some getting around 95% (?) efficiency. Not sure the exact number on heat pumps, but I bet it's similar!

[MattKatz]

Ya know.....HE could have went with far worse.....

An Electric Furnace....Even though its 100% Efficient.

[jporter12]

Ya know.....HE could have went with far worse.....

An Electric Furnace....Even though its 100% Efficient.

Eeeww. Been there before! Aplace I used to live had forced air electric "heat". VERY expensive, and not very warm. The owner switched to propane to go with his heat pump, and the bills were MUCH less.