troggy02

We have a large well insulated house and 18kW capacity ASHP and the house is toasty warm at -7c (last winter). I'd suggest your friends system in improperly installed or spec'd in some way.

Sadly no. I contacted Samsung support who put me in contact with a couple of their expert suppliers but both were useless. Their advice consisted of telling me there was no reason why it couldn't and advising that cooling the slab my crack it! The unit has specific settings for slab cooling (UFH) and limits the temp to 19c. I suspect my next step is to pay them to come on site. We could of course install separate air conditioning pumps, but we dont want large units sitting around the house for the 5 daya a year we need them. Especially when there's a really big one that could do the job already there!

Curious, ours continues to extract heat until the unit is solid white at the back. In your picture it looks pretty unobstructed, so maybe defrosting a little early?

Thank you - very interesting. Our Samsung runs in reverse to defrost. I must say it's pretty quick actually. From talking to the engineer, the unit runs the fans faster and compressor less near zero in an attempt to obtain the same heat extraction without pushing the heat exchanger past zero. 20201127_104210.mp4

You should only really get frosting between approx 2 and -3c depending on humidity. Our system is designed for a 35c flow temp at -3c. At one point we increased this by 2c mainly as an experiment and it caused significantly more defrost cycles. Back to its original settings it might defrost once every 45 minutes worst case (freezing fog appears to be the worst). It's -1c outside as I type this and while I can see frost on the unit, it's been cycling on the thermostat for several hours without needing to defrost.

For me it's a tech item to play with ?. The filters definitely definitely don't last more than 6 months, they're pretty black by then. There are times when it's useful to boost the circulation, smelly cooking for example. Currently activating boost requires me to crawl in to the cupboard and press the button. Even if it didn't, the units on the 3rd floor and kitchen on the ground. Yes, I could get an extended display but don't you think an app is do much cooler! Seriously though, I like to know what the bypass is doing and what it thinks the internal and external temperatures are. Partly this is because I'm not convinced it's working as designed. Once it's switched in to overnight bypass it should switch back to normal once the internal temp hits the set point, but ours continues until it's hit the time limit before finally switching. I had a case open with Vent Axia last year, but then the weather cooled and I was not able to diagnose any further.

Looking for advice on an Samsung ASHP. During the hottest summer days I'd like to cool the floors. We can debate how effective this is likely to be in a different thread, but for here I'm looking for help solving why I can't get it to switch. If I connect a thermostat to the designated inputs for cooling in the control kit, I can see cooling selected if I put the control panel in to diagnostic mode. On the panel itself however, the mode button does not change the "operation" mode from heating to "cooling" or "auto". It's locked in heating. In the service mode settings cooling is enabled. I've read that ASHP sold under the RHI scheme are locked to heat only, but our house is a new build and not eligible for RHI. Is it possible this unit is locked? and if so how can I get it unlocked. Any advice gratefully received.

It's a Vent Axia sentinel kinetic plus. With what I know now and given the choice I would have gone for the LO-CARBON SENTINEL KINETIC ADVANCE which is more expensive, but I like the idea of wifi access to it.

To clarify then... The ASHP can produce UP TO 18kW of heat, but would never need to produce anything like that normally. At 8c it's real life continuous use is around the 1.5kW mark. Right now it's about 1.5c outside, about 60% of the UFH is on + first floor radiators and it's consuming 2kW with a flow temp of 37c. At -4c I've seen it rise to 4Kw. I believe the max it can draw is 5kW. Obviously it will vary according to load. The heat loss calculations for the property show a 7.6kW requirement at -3c. The design model uses an average COP of 2.68 at -3c and season average of 4.31.

We have the house at 21c, but note, the thermostats for the UFH have to be at 23c to obtain that. We have a couple of accurate weather stations and traditional thermometers that all confirm the 21c actual temp. I think the room stats just aren't that accurate. Energy wise you're in our ball park. On a very cold day (say -3c) we could consume 40+kWh to heat the house and water or more. It's worse when between 2 and -3c, humid and ice forming on the ASHP due to the defrost cycles. Either side of that its pretty efficient.

The heat consumption looks way too high. Bare in mind that your ASHP will be around 3 x efficient. Ours for example consumes around 1.5kWh with the outside temp around 8c rising to 4-5 kWh at -3c. It's producing up to 18kWh of heat for a largish property. I estimate we'll use about 12,000 kWh per annum with 2 x electric cars! Tariff wise we're with Octopus. We were with the Agile tariff that variable and on some days gets down to a few pennies a kw, but it can also rise to 35p kWh. We've now moved to Octopus Go which is 13.8p during the day and 5p from 0:30 to 4:30am which is good for heating the house overnight (and the cars).

Interesting read, and certainly can't comment on the cost argument, but thought I'd share our experience. We moved in to highly insulated new build one year ago. I'd describe it as a semi-passive house in so far as we can normally maintain around 21c down to about 8-10c outside without heating, and then with very little until it gets towards zero. It's a fairly large property with Samsung 18kW ASHP. We previously lived in a new Persimmons house (and that's a whole other story!). What we've noticed: When you walk in to the house, it never has the familiar odour that most homes do. It just smells like the outside. My wife's a keen cook. The kitchen is designed without a hood, but any degree of smell in the house clears within an hour completely even though the house is open plan. We live in the country but its amazing how many pollutants the filters remove. Especially when neighbours have their log fires lit! Anybody with hay fever loves our house. They get instant relief from the moment they enter. We don't suffer from cold spots in rooms, or rooms that are a different temperature to others. Cloths hung inside dry far quicker than in previous houses. The house humidity is very stable all year round. During the summer when it was 35c outside, we were able to maintain 26c in doors with fresh air - heat recovery works both ways of course. When the outside temperature drops at night, the MVHR goes in to bypass mode with boost to help remove excess heat from the house. Throughout last summer this was a God send, especially since we get considerable solar gain from our windows. I've configured the unit to drop from it's regular 58% to 30% overnight. As others have said, the standard setting is unnecessary over night both from a power and noise point of view.