Air Source Heat Pumps

samtheman1k

If you're house is getting to -5deg C, then something is seriously wrong in your house. I left my house with no heating 2 years ago for 3 weeks during that really cold period, arrived home when it was -9 outside, but still only +7 inside (with no heating for 3 weeks). If your house is -5 inside, then you seriously need to get some insulation sorted, heat pumps or no heat pumps!

TiredGeek

samtheman1k wrote: »

If you're house is getting to -5deg C, then something is seriously wrong in your house. I left my house with no heating 2 years ago for 3 weeks during that really cold period, arrived home when it was -9 outside, but still only +7 inside (with no heating for 3 weeks). If your house is -5 inside, then you seriously need to get some insulation sorted, heat pumps or no heat pumps!

This is northern Scotland here, not far from that Altnaharra that made the news. An unheated house, with outdoor temps of -17'c to -23'c for ten days solid, I think it did well to stay as warm as -5'c
More insulation isn't an option, there is simply nowhere to put it....

richardc1983

TiredGeek wrote: »

This is northern Scotland here, not far from that Altnaharra that made the news. An unheated house, with outdoor temps of -17'c to -23'c for ten days solid, I think it did well to stay as warm as -5'c
More insulation isn't an option, there is simply nowhere to put it....

TiredGeek,

Your house should have been at 10C not -5C, the system shouldnt have had any issues.

I emailed you last night.

thechippy

richardc1983 wrote: »

Doesnt seem like your the only one with defrosting problems on air/water system!

This seems to be worse than yours and is over in Netherlands: Its a Daikin Altherma!

http://www.refrigeration-engineer.com/forums/showthread.php?t=29513

I don't think the defrost cycle is working correctly on that. Do you?

......:D

richardc1983

thechippy wrote: »

I don't think the defrost cycle is working correctly on that. Do you?

......:D

Apparently its becoming a common thing... this unit is installed on a roof and has had ice, rain and snow blown directly at it.

Its the grill around the back that bridges the snow and ice together so even though the coil thinks it has got back upto temp at the end of the defrost cycle the ice is still all over the grill on the back.

thechippy

Change the location of the coil sensor methinks....

grahamc2003

thechippy wrote: »

Change the location of the coil sensor methinks....

I'd say enclose the unit in a something like a fine mesh, to let the air in and keep the snow and rain out. And also turn the whole thing off if icing gets too bad - no point in flogging a dead horse.

richardc1983

But isn't the mesh then going to get covered in snow and block air flow off even more? It needs some sort of canopy over the top to shelter direct snow. You will still have an issue with snow being blown by wind and the high air currents from the fans.

grahamc2003

richardc1983 wrote: »

But isn't the mesh then going to get covered in snow and block air flow off even more? .

I was thinking of something like nylon, as in tights, but stronger. I doubt snow would stick to any vertical nylon, which I expect would protect the side vents. I'd just be careful not to let the nylon get ripped and injested! But it would be a case of giving it a try - i think a physical barrier is necessary to stop snow and rain getting inside. Also, I think having the unit wall mounted instead of on the ground would help too.

It'd be really interesting to see how any air to air units worked in the very cold weather - Steve's electricity usage readings would be really interesting, as too his observations on how often his units froze up and whether his units' defrost strategy worked well.

Cardew

grahamc2003 wrote: »

I'd say enclose the unit in a something like a fine mesh, to let the air in and keep the snow and rain out. And also turn the whole thing off if icing gets too bad - no point in flogging a dead horse.

Graham,

I have a couple of cages in my garden, one with a 2" mesh and the other with a 1" mesh.

In the weather in Dec both meshes were completely blocked with a combination of ice and snow.

Edit,
Just seen your post on Nylon and that might work as I have some netting for strawberries that was left out and the mesh on that that wasn't blocked.