Heat pump defrost cycle - what happens? I thought our heat pump had blown up!

[@joshuam5826]

Thank you for the great content you create, it's extremely helpful I'm due to begin my retrofit project in late Jan from Oil along with a raft of other energy measures, needing to have a upgraded new three phase supply fitted from the roadside by the DNO to a new meter box externally (32m in total) a smart meter with isolator, consumer unit/tails, smoke alarms, Heat Pump with a wireless controller for auto Adaption function & concrete foundation for it to stand on, hot water cylinder, 13 new rads, pipework, insulation/Plastering in the loft room, solar panels, inverter, battery storage system, Zappi EV charger point, loft boarding, lighting & lastly a new concrete path round the exsternal of the house. So going to have a house full of contractors

[@TomBray-LowCarbonLifestyle]

Hi Joshuam, thanks for the comment, really pleased to be of help. That is a really exciting project and great to hear, complete transformation! Well done for making the move, would be great to hear more as you progress. Hope it is as pain free as possible! Tom

[@edwardpickering9006]

You know what, I never knew that's what a defrost cycle actually did! And very visually impressive...

[@TomBray-LowCarbonLifestyle]

Absolutely, a bit of a surprise first time you spot it!

[@TomBray-LowCarbonLifestyle]

Happy new year Edward!

[@Legg99]

Oh boy - you are so right! We have just had a heat pump; it's been running for 3 days now so very new. Like you I'm a degree qualified physicist & engineer and had done loads of research and thought I knew all about heat pumps. And then this morning I noticed it had gone quiet, the main fan had stopped and the flow temperature was way down, and there were wisps of vapour (looked like smoke) coming off it!!! Yes just like your video. Then as I approached it blew the vapour straight at me. Just as I was staring to panic I remembered 'the defrost cycle'!! And then I Googled it and found this excellent video. Phew!!! They should make this video compulsory viewing for all new heat pump owners. Thanks for posting.😃

[@TomBray-LowCarbonLifestyle]

Amazing! Pleased to hear my video has been helpful! It’s quite the shock isn’t it?! Thanks for commenting and engaging with the video! Tom

[@M0PAX]

Thanks for the reply glad it’s all in correct as you said shame about the side access. As an electrician access is always, oh didn’t think of that 😂

[@TomBray-LowCarbonLifestyle]

Fair enough! Something the installer should have done right, but hopefully will be ok in the long term Tom

[@Simon-kq1xu]

Haha, my installer warned us about the clouds of steam! Before Xmas I did a review of the first year's use of electricity and our ASHP, with our SCOP at 4.8 average the cost was under £95 a month across the year. Very chuffed, less than when we used gas. Unfortunately Octopus is not good at accepting we don't use gas, unnecessary stress that is ongoing

[@TomBray-LowCarbonLifestyle]

That’s fantastic efficiency and a great example for others to hear. I know our neighbour has had issues with octopus not believing that gas connection has gone… fairly frustrating! Happy New Year! Tom

[@Umski]

Quicker than I was expecting, how often does it run a defrost on a similarly cold day for example?

[@TomBray-LowCarbonLifestyle]

Good question and I am not sure, that was one defrost in about 35minutes of filming, so maybe at 0°C it is defrosting 1-2 times per hour - 90 mins. But that’s a guess!

[@nic47531]

Hi, im considering a HP. Question.. Heat pumps have a compressor in them which I've seen in other videos can be like a loud freezer, when its pump runs, obviously freezers dont make sound all the time. Does the sound of the compresser/HP transfer into the house? Our current gas boiler can transfer sound through pipes when heating is on depending on how much flame is burning.

[@brackcycle9056]

Does heat pump site have any effect on number of defrost cycles , Is a north side location in damp boggy garden worse ? How many defrosts do you get per hour ?

[@TomBray-LowCarbonLifestyle]

Interesting questions... I am sure that the site would have impact, you can imagine that a windy location could impact frost build up, and you could imagine if it was in a particularly wet area, that could also contribute... I guess this is getting into quite specific micro-climate issues that I suspect won't effect most installations. I don't know how many defrosts we get per hour, and will vary on temperature / weather etc. I had set my camera up for about 30mins on a day at about 0°C so at max it would be twice an hour that day. But I suspect much less. Thanks for engaging with the video! Tom

[@tarkadahl1985]

I track everything via home assistant, the power consumption pattern completely changes when it defrosts so fairly easy to see, most I've seen was two in a day but its obviously very weather dependant.

[@TomBray-LowCarbonLifestyle]

Thanks @@tarkadahl1985 - that is very interesting!

[@acer8]

The Ecoexperts link doesn't give you a heat pump quote directly, by the way. They just sell your details to local companies.

[@TomBray-LowCarbonLifestyle]

Hi Acer8 - yes I wouldn't necessarily trust a site that didn't connect you with real companies, linking you up with local installers would be key to getting a thorough quote. Thanks Tom

[@kayokun3395]

So helpful!

[@TomBray-LowCarbonLifestyle]

Thanks for commenting, really pleased it is helpful!

[@terryrigden4860]

Thank you, that could save me some anxiety

[@TomBray-LowCarbonLifestyle]

No problem Terry! Happy New Year!

[@MikeGleesonazelectrics]

It can use just water, not necessarly refrigerant, as in my case. Also i dont think it compresses the liquid, its the air it compresses i believe. This increases its heat capacity begore it goes thru the heat exchanger. But thanks for the video, took me by surprise the first time too!

[@TomBray-LowCarbonLifestyle]

HI Mike, apologies if I caused any confusion. I was talking through the heat pump process to explain why frost would occur, but yes, a defrost just uses hot water from the building heating system. Compression in the system is of the gaseous refrigerant after it has been heated and evaporated by the heat exchanger, this is within the heat pump process and we don't see it outside the unit. The air is not compressed. Thanks for taking time to comment Tom

[@lharris828]

I had a similar panic just hours after our installation when I saw the power consumption rocket despite the water and heating being off!!! After considering trying to contact them at 10pm!, I decided to wait for 10 mins to see what happened. Then all went normal! No explanation whatsoever in the manual. Why don't the installers consider these things? I decided that it was an unannounced defrost cycle. There are much easier ways to give people heart attacks!

[@TomBray-LowCarbonLifestyle]

Oh no! There are definitely a lot of new things when you have a heat pump, and difficult to know what is 'right'... but pleased to hear yours settled down! Tom

[@M0PAX]

Just an observation may be wrong? from watching other videos on heat pumps they talk about air being pulled back into the unit if walls fence is to close, your unit looks like it doesn’t have enough space on the sides for the unit to exchange air hot or cold. This could lead to the unit running harder and shorting its life and cost you more to run. kzbin.info/www/bejne/Z6Ouf4dtYpllgJIsi=Eq68E6qoe6GkgKNo go to time point 27:10 and they talk about air flow on the unit.

[@TomBray-LowCarbonLifestyle]

Thanks M0PAX, you're not the 1st person to point out this or ask the question. I have reviewed the minimum clearance for the unit vs the manufacturer's literature, most of the dimensions are fine, the access space on the right hand side is smaller than required, which is pretty frustrating! But hasn't been a problem with servicing so far over the 1st 2.5 years. I think the space at the rear and other side for ventilation is larger than manufacturer guidelines. Thanks for taking the time to comment. I think this video with Roger Bisby and Adam Chapman is fantastic, and amazed to see how much Roger Bisby is won over by Adam. Thanks Tom

[@AdamDitheridge]

It's condensing water vapour....not steam.....

[@TomBray-LowCarbonLifestyle]

Hi Adam, not sure what you are referring to, but water vapour / steam are fairly similar words referring to similar things, i.e. water in the gaseous form. I don't say that either water vapour or steam is condensed in the heat pump process. Thanks for engaging with the video Tom

[@simonblurton8009]

It's so quiet

[@TomBray-LowCarbonLifestyle]

It is pretty quiet - I did a video about how quiet over here - kzbin.info/www/bejne/oaTVco2DYtGXf5osi=k_BHbVM50o7hZQ59 Thanks for engaging with the video Tom

[@fryske.tynster]

your a .....no offence and a tip that heatpump is installed bad distant to the wall is far to small to the % is minus 50 at least.

[@TomBray-LowCarbonLifestyle]

Hi Andre, I am not sure what the dots mean? Yes you are right the distance on the right is smaller than the manufacturer’s recommended distance. I understand this is for access for service. Hasn’t caused any problems in the first 2.5 years and hope it doesn’t in the future. Thanks for pointing it out. You aren’t the first person. Tom