Heat pump coil covered in snow and ice?

Xringer · 02-27-11, 09:01 AM

Every time it snows here, it seems like the Sanyo Mini-split is doing way too many defrost cycles..

I've used these Frost King wires on my roof & gutters for years and they work okay.

Amazon.com: Frost King Roof & Gutter De-icing Cable Kit RC 120 Ft (Model RC120): Everything Else

So, I'm thinking of adding a bunch of hot-wire loops on the surface of the air intake area of the outdoor coil.

Maybe even on the side too.

These pictures were taken After a defrost cycle (or two maybe)..

I think about 400watts would work okay, and perhaps it could be controlled remotely using an X10 module..

I know the wire will melt light snow pretty quickly at normal winter temperatures. And I know that 400watts will about double our power use during snow fall.
But, I'm wondering how much of that 400watts(1,365 BTUh) of heat will be
captured by the Sanyo coil & pumped inside?? Maybe 30%??

Comments are welcome.

Thanks,
Rich

Daox · 02-28-11, 06:48 AM

Wouldn't the defrost cycle be more efficient?

Xringer · 02-28-11, 07:42 AM

I'm not sure. With the current temps, I'm seeing 1200 to 1500 watts being used during defrost cycles.
During that time, the room temp drops and Aux heating kicks in.

That can be Oil and/or Electric space heating. Which we know costs a bundle.

After the Sanyo defrosts and rests a few minutes, it comes back on in High-Power mode.

I hate that! It just did it again.. The power just shot up to 3,000 watts..
That's above spec..

No snow today, just some frozen rain. Which can't get into the air in-take..

BUT, the weather is perfect for a lot of defrost cycles!

27.8°F
Humidity: 94 %
Baro: 29.90 In

Just have to turn it off until the weather gets better..

Daox · 02-28-11, 09:18 AM

Is there no way to disable the high power mode? Or no way to set a larger temperature difference before it kicks in?

Xringer · 02-28-11, 09:59 AM

It seems the High Power mode is built into the firmware.
I think it's part of a 'quick heat' routine they use to quickly recover warmth lost while defrosting.

I've tried to bypass the defrost-to-High power jump, but turning down the
set-point on the remote/T-stat. (During defrost)
If it's 21c in the room, and I select 18c, it makes no diff. It still surges.

When the out-door temp is pretty good, sometimes (rarely) the surge isn't
too bad. It goes up to 2kw and then steps back down..

There is actually a High Power button on the remote.
It's good for a quick climb to 3.6 kW.. (Meaning it's worthless)!

Right now, it seems like the excessive power use is caused by
too much R410A in the system. I'm planing to do a pressure test
to see if this bug can be ironed out..

In the summer, we didn't have any problems with these surges.
No defrosts required and we didn't call for more cooling too fast..

Just move down the set-point, wait a while (for the power to settle)
and repeat. Just have to baby the system..
The cooling is fantastic..

02-27-11, 09:01 AM	#1
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	Heat pump coil covered in snow and ice? Every time it snows here, it seems like the Sanyo Mini-split is doing way too many defrost cycles.. I've used these Frost King wires on my roof & gutters for years and they work okay. Amazon.com: Frost King Roof & Gutter De-icing Cable Kit RC 120 Ft (Model RC120): Everything Else So, I'm thinking of adding a bunch of hot-wire loops on the surface of the air intake area of the outdoor coil. Maybe even on the side too. These pictures were taken After a defrost cycle (or two maybe).. I think about 400watts would work okay, and perhaps it could be controlled remotely using an X10 module.. I know the wire will melt light snow pretty quickly at normal winter temperatures. And I know that 400watts will about double our power use during snow fall. But, I'm wondering how much of that 400watts(1,365 BTUh) of heat will be captured by the Sanyo coil & pumped inside?? Maybe 30%?? Comments are welcome. Thanks, Rich

02-28-11, 06:48 AM	#2
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	Wouldn't the defrost cycle be more efficient? __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

02-28-11, 09:18 AM	#4
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	Is there no way to disable the high power mode? Or no way to set a larger temperature difference before it kicks in? __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

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02-28-11, 07:42 AM	#3
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	I'm not sure. With the current temps, I'm seeing 1200 to 1500 watts being used during defrost cycles. During that time, the room temp drops and Aux heating kicks in. That can be Oil and/or Electric space heating. Which we know costs a bundle. After the Sanyo defrosts and rests a few minutes, it comes back on in High-Power mode. I hate that! It just did it again.. The power just shot up to 3,000 watts.. That's above spec.. No snow today, just some frozen rain. Which can't get into the air in-take.. BUT, the weather is perfect for a lot of defrost cycles! 27.8°F Humidity: 94 % Baro: 29.90 In Just have to turn it off until the weather gets better..

02-28-11, 09:59 AM	#5
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	It seems the High Power mode is built into the firmware. I think it's part of a 'quick heat' routine they use to quickly recover warmth lost while defrosting. I've tried to bypass the defrost-to-High power jump, but turning down the set-point on the remote/T-stat. (During defrost) If it's 21c in the room, and I select 18c, it makes no diff. It still surges. When the out-door temp is pretty good, sometimes (rarely) the surge isn't too bad. It goes up to 2kw and then steps back down.. There is actually a High Power button on the remote. It's good for a quick climb to 3.6 kW.. (Meaning it's worthless)! Right now, it seems like the excessive power use is caused by too much R410A in the system. I'm planing to do a pressure test to see if this bug can be ironed out.. In the summer, we didn't have any problems with these surges. No defrosts required and we didn't call for more cooling too fast.. Just move down the set-point, wait a while (for the power to settle) and repeat. Just have to baby the system.. The cooling is fantastic..