Author Topic: Turning Heat Pump Totally Off for a few days of zero degree snowy icy weather  (Read 665 times)

slackmax

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Hi,

I figure no one really knows the answer for sure, but I can't resist asking anyway!

If you want to avoid reading the entire post, the basic question is whether leaving a heat pump off completely and letting it get covered in snow and ice for a few days would hurt it. My assumption is that it would not.

I'm trying to maximize the life of my 20 year old heat pump. It is working fine right now. I haven't had a tech touch it since it was installed.

I have had it running this winter, normally, except that I keep the house pretty cold, around 52 degrees day and night (You get used to it!)

And that's during days and nights that are about 30 something in the day and 20 something at night (pretty mild).


But nighttime lows are going to be around zero for a few days in the near future, along with rain, ice and snow. Snow could be about 8 inches, not too bad.  But if there is enough rain, I could get water pooling at the bottom of the heat pump slab, maybe rising up into the fins and coils of the unit too, and maybe freezing, who knows.   (I usually do get the classic big blob of ice around the compressor each winter and it doesn't seem to hurt anything).

So, I'll get to the point:  Will having my heat pump off and letting the snow and ice and rain do whatever it wants to do, result in harm to my heat pump?

I don't want to be going out at 2 AM in zero degree weather cleaning snow and ice off, or bailing water away from it (it is in a sunken area that pools with water during heavy rain) and my hope was that I could just leave the heat pump turned off,  let nature do its thing, then let it melt away later, or pour water over it to help it melt later, whatever.

I would be heating my house with kerosene and/or a plug-in oil filled electric radiator.  I'm not real concerned with the cost of the kerosene or the electricity, but very concerned about preserving the life of my heat pump. And if I left it on it would be running non stop for a few days, I think, if temps are down around zero.

I'm wondering if water would seep into the inner workings of the heat pump, or just being so cold for so long, and not going through its usual cycles would hurt it somehow. 

Sorry for such a belabored post.

Thanks   



 
 

Jon Bon

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Ok this sounds kind of like a terrible idea to save a buck.

To answer your original question I think the exterior unit of your heat pump would be fine. They are built to be weather proof. (im not a HVAC tech or anything) I mean it does fine in driving rain and snow. Sure like 10 feet of snow on top of it would be bad for it, as it would be anything.

More likely you are going to freeze some part of your house due to uneven heat. Pipes break and then your basically screwed.

Correct me if im wrong but your heat pump is going to go into emergency heat mode anyways right? Super cold temps heat pumps cant really do their job and they go to old fashioned resistance heating. If your heat pump cant do its job with out breaking then you need a new heat pump.

Also get some sort of stand for your heat pump if water is pooling around it. I mean a partially submerged unit would be bad news.  I think you can just buy a plastic stand or just put a few cinder-blocks under it.

I mean I get it, my wife left for the weekend and I kicked the heat down a few degrees, but this seems a bit nuts.




bacchi

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Yes, definitely make/get a stand for it.

Your heat pump will also run more efficiently if it has a roof above it to keep the snow away.

slackmax

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Yes, definitely make/get a stand for it.

Your heat pump will also run more efficiently if it has a roof above it to keep the snow away.

Now that I think about it some more, I wouldn't want ice building up on the coils, expanding and cracking them, possibly. By letting the unit run, it would be defrosting occasionally and getting rid of ice directly on the coils. The ice that builds up on the condenser doesn't seem to hurt anything. Of course I  could just cover it all with a big tarp, and turn the heat pump off, but I'd still have the problem of the water rising.

About raising the unit:  I want to be very careful not to disturb any of the pipe fittings that carry the freon in and out. So I can't move it very much at one time.  I'm thinking of just getting a shovel under one side of the slab, prying it up an inch or so, and stuffing dirt under it as much as possible, then doing the same thing to the other sides, and making sure it is pretty level. 

And I wonder if the ground has really sunk that much in 20 years, or whether the water just isn't draining away properly anymore.     


« Last Edit: January 18, 2019, 06:43:43 PM by slackmax »

HipGnosis

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I think you should have the unit serviced - 20 yr is WAYY overdue.
It may be low on freon which makes it really inefficient.
Ask the tech while he's writing up your bill.

Syonyk

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What problem are you trying to solve, exactly?  That a heat pump that's ran for thousands of hours over the past 20 years will somehow fail if it runs a few more?

I don't think running will hurt it, and I don't think shutting it down will save it - it shouldn't really matter one way or the other.  However, there are a few things you should take care of.

The whole "talking on water" thing should be resolved with either raising the unit or adding a drain ditch/pipe/whatever.  Raising the unit sounds like a better plan, but as noted, those hose connections are somewhat fragile, so don't just yank it around.

A heat pump install will almost certainly have backup coils, though, and you should look at the datasheet for your unit to figure out when the system is more efficient to run on the coils (big resistors, 1kWh electrical = 1kWh heat).  Below a certain temperature, which is probably above zero for a 20 year old unit, the efficiency drops below 1 - you'll use one unit of electricity to pump 0.7 units of heat.  At that point, you're better off with the coils.  My unit is good to -10 or -15F before that happens, but it's only a few years old.

But, really, at this point, 20 years old for a heat pump is somewhat beyond the expected service life.  New units are a good bit more efficient and work down to lower temperatures, so it might be worth budgeting for a replacement.

BudgetSlasher

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If it has been running for 20 years it certainly has encountered conditions like you are expecting before and survived. If it were to go out now, I would suspect it was soon to go out from one cause or another.

If you truly want to maximize its life span I would recommend addressing the issues with drainage, a platform for the unit, and/or some sort of show shield/roof.

I agree with syonyk it should have some sort of electric backup (even my parents 25 y/o heat pump in Florida has electric resistive "emergency heat").

If this one goes out, I suggest remembering this and relocating the exterior unit to a more appropriate location.

kenmoremmm

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my heat pump is controlled by my thermostat to shut off below 35. heat pump is 1999 model, so same age as yours. so, my answer is that it's going to be shut off below the temps you're worried about, but that i wouldn't worry about it anyway.

i heat with wood, so the heat pump is only used a month or two out of the year when temps are in the 50-60 degree range.

i cannot imagine how your house would get that cold. do you have insulation? it would take a long long time for my place to cool down to that level (1979 construction). i could heat it to 70 and it would last a week until it made it down to 52.

slackmax

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What problem are you trying to solve, exactly?  That a heat pump that's ran for thousands of hours over the past 20 years will somehow fail if it runs a few more?

I don't think running will hurt it, and I don't think shutting it down will save it - it shouldn't really matter one way or the other.  However, there are a few things you should take care of.

The whole "talking on water" thing should be resolved with either raising the unit or adding a drain ditch/pipe/whatever.  Raising the unit sounds like a better plan, but as noted, those hose connections are somewhat fragile, so don't just yank it around.

A heat pump install will almost certainly have backup coils, though, and you should look at the datasheet for your unit to figure out when the system is more efficient to run on the coils (big resistors, 1kWh electrical = 1kWh heat).  Below a certain temperature, which is probably above zero for a 20 year old unit, the efficiency drops below 1 - you'll use one unit of electricity to pump 0.7 units of heat.  At that point, you're better off with the coils.  My unit is good to -10 or -15F before that happens, but it's only a few years old.

But, really, at this point, 20 years old for a heat pump is somewhat beyond the expected service life.  New units are a good bit more efficient and work down to lower temperatures, so it might be worth budgeting for a replacement.

Yes, I'm just trying to eek out a few more hours, days, years of service from the heat pump. Plus I hate the fact that prices for installation of heat pumps (outside unit and inside)  have tripled in the the last 20 years. I only paid about $1,200 for my outside unit 20 years ago, including installation labor. And my inside unit (air handler) is 30 years old,  so I'd probably voluntarily replace that too. Total hit for inside  and outside  replacement would be around $6,000 to $7,000.  And apparently a huge amount of that in 'labor'.  One day of labor from them to install the units equals around $3,000.  That galls me.  Would like to postpone that ripoff as long as possible. Not going to install it myself!     Don't want to buy the units online and have a Craigslist installer.

Yes, my setup has resistance heat for backup when it gets too cold. The blue light comes on and the heat is hot!   

The water rising up around it :   I can only surmise that the ground around my house has been gradually settling for some reason. I don't remember having this pooling problem until about 10 years ago, and the first time I noticed it was actually rising up around the heat pump was this year during a 4 inch rainfall. I have extended the downspouts farther away from the foundation, but the main problem is that the yard slopes toward the house everywhere except for one corner of the front yard. I've got a few extensions on the the front yard downspout which brings (most of it during heavy rain, but none during light rain) the roof water into the yard where I think it is flowing down to the corner of the front yard, then pooling there and overflowing over my driveway into my front yard on the other side of the driveway, and disappears into a hole.

I don't know if a 4 inch rainfall will still flood the heat pump. But some 1.5 inchers have stopped at the top of the cement pad, so maybe the extended spouts are working.

I agree that raising the heat pump is in order. 





« Last Edit: January 22, 2019, 08:19:15 AM by slackmax »

Syonyk

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Yes, I'm just trying to eek out a few more hours, days, years of service from the heat pump. Plus I hate the fact that prices for installation of heat pumps (outside unit and inside)  have tripled in the the last 20 years. I only paid about $1,200 for my outside unit 20 years ago, including installation labor. And my inside unit (air handler) is 30 years old,  so I'd probably voluntarily replace that too. Total hit for inside  and outside  replacement would be around $6,000 to $7,000.  And apparently a huge amount of that in 'labor'.  One day of labor from them to install the units equals around $3,000.  That galls me.  Would like to postpone that ripoff as long as possible. Not going to install it myself!     Don't want to buy the units online and have a Craigslist installer.

Ok... seriously, I don't think shutting it down for some heavy storms is going to meaningfully impact life.  It'll either die when the motor fails, or when the refrigerant leaks and the now non-lubricated compressor seizes.  Other stuff should be easy to fix.

$1000 in 1997 is around $1500 today based on some inflation calculators, so your cost math is a bit inaccurate.  And modern units are a good bit more efficient, which saves you money - those backup coils are quite expensive to run.

I had a 2.5 (or 3?) ton unit installed for a lot less than the prices you're getting, so you might want to shop around.

If it's been running for 20 years without trouble, seriously, just let it do what it's been doing, and fix it so it's not literally sitting in water.  The rest of your plans are just goofy.

EricEng

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It won't hurt your heat pump to sit in the cold unused.  Your house is another story, but your heat pump will be fine if you want to turn it off.  Throwing a tarp over it to keep the snow out would help when you are ready to reuse it.

Keep in mind that just because the air inside your house is 50 degrees, your pipes in exterior walls will likely be much cooler.  I had a house where a water pipe in an exterior wall would freeze if I left the air temp reach 60.