Heat pump / inverter DIY

Hermann

housesitter wrote: »

Hermann: I'm beginning to think that the best bet for doing this might be a mobile car air con guy. A guy I know on/off (tho other side of the country) does A/C regassing and system evacuation plus leak testing for cars.
perhaps worth a call to one of them?
They generally use a different gas (R-134a instead of R-410A quoted in your manual), but I'd figure it's similar proceedure wise ?
I wonder why the different gas too ?

I think the different gases allow for being cfc free and run at higher pressures.
I believe the R410a gas allows for a much more efficient system.

The car aircon guys might be helpful but I'm not sure they use Nitrogen and Vac pumps of this order. As for regassing for domestic installs I believe you need to be a registered person (Corgi?) to deal with the gases. Car guys probably couldnt get the right gas or have the correct fittings. R410a systems have subtly different connectors due to the higher pressures.

As far as the gas goes I think DIYers are stuck with precharged systems and no leaks! If it leaks/fails I can't see any alternative but to get it regassed by a registered engineer.(If anyone knows different please tell! )

thechippy

To answer some questions.

1. Different refrigerants are used in different applications as they all have different boiling and condensing points. R410a is extremely efficient at absorbing and moving heat, although it runs at considerably higher pressures, than for example R134a.

2. Nitrogen should NEVER be used by the untrained. The bottle pressure starts in the region of 2900psig. You will also need a £200 regulator to attach to the bottle. Unskilled people have been KILLED using nitrogen.

3. R410a requires a special set of service guages to be used to cope with the higher pressures. Standard service guages should not be used.

4. Refrigeration pipe is different to plumbers pipe - it is nearly pure copper and the sizes are measured in OD and not ID. Suitable benders are required for the pipe, as is a flaring tool to make off the ends. The flaring tool is NOT the same as the ones used for flaring brake pipes on a car.

5. It has been illegal for some time to install a refrigeration or air conditioning system without being suitably qualified, unless it comes with pre-charged lines (pipe) with special connectors at each end and even this is now dubious.

6. The "self install" systems are generally poor quality and have little to no technical or spares backup.

7. You can rarely install the pre-charged pipes neatly, as you can't bend them neatly due to the fact that you can't use a bending spring at all and the insulation prevents the correct use of hand benders. If the pipes are longer than needed, you need to "lose" the excess somehow, as you cannot cut and shorten them.

Cardew

Hermann wrote: »

If I was doing this in Kent I'd take the gamble that outside Temps will be fine for an ASHP. In the past 10 years how often have outside temps been under -5 all day? I suspect very rarely if ever. :beer:

Nice post.

IMO the possibility of a really cold snap is not an issue. It rarely happens and if it did a £20 fan heater to supplement will solve the problem.

richardc1983

Latlum wrote: »

The good news is it will be well insulated but bad news is I reckon it will be VERY hot, probably unbearable up there in the summer.. 4 velux windows all south facing. So I should think about an air/air heat pump to do the heating and the cooling.

Maybe use the same air heat pump for the flat? Except the pool is about 40 feet away from the flat.

Am in a muddled state.

The heat pump u use to heat the pool and flat will be two different systems. They work totally different to the comfort cooling unit in the flat so you will need two separate systems.

ALso consider blackout reflective blinds for the velux windows. We had these and bought them from velux helped reflect alot of that hot summer sun and thus kept the space from getting too hot however cooling was still needed. make sure you get the velux ones, they are a bit more expensive but they fit perfectly.

stevehead

Cardew wrote: »

Nice post.

IMO the possibility of a really cold snap is not an issue. It rarely happens and if it did a £20 fan heater to supplement will solve the problem.

Not really... at -5C you get just as much heat out as at +5C, but you do need more 'cos it's colder.
The heat pump efficiency will have dropped considerably, but not to the point where a fan heater is cheaper.

I don't think that the plumber that's coming round to look at your heating will be the best source of advice; plumbers do what plumbers do...
Let the plumber deal with the DHW, and ask an aircon firm to cost the space heating / cooling. Post here the system they suggest, and let us review it for you

richardc1983

Steve

As the outside temp gets colder the output drops so the unit has to work harder to output the same heat as it would at +5C. So on older units they output less heat as cannot extract much from air at -5C however newer units still have 80% capacity at -15% any colder they start to lose output rapidly.

The fact that they still have 80% capacity at perhaps -5C to -10% means that you have lost 20% capacity so this means that the outdoor unit is outputting 20% less heat than it would if it was +5C.

However at -5C if the unit is sized correctly you will certainly not have to get the fan heaters out. Only at -15C would you start needing to think about getting the fan heaters out to assist the unit but this would never be the case really in the uk.

Cardew

stevehead wrote: »

Not really... at -5C you get just as much heat out as at +5C, but you do need more 'cos it's colder.
The heat pump efficiency will have dropped considerably, but not to the point where a fan heater is cheaper.

I

COP the same at -5 as +5C?

I wasn't stating, or even implying, the fan heater was cheaper.

Hermann was questioning if the ASHP could cope with -5C. I was mere stating that a fan heater could be a standby to boost the ASHP heat output to make it warm up quicker.

rothers8080

The plumber also did aircon work, which is why he had a vacpump, they also sell aircon systems too.

You can buy a vac pump for these aircon systems for around £120. I think I'm going to get one as we are planning on installing another unit now in our garage, this will mean we are 100% on heat pumps

I'd not try to use something else to do this, the unit I used was for aircon pipes and had gauges to measure it. If you wanted to be certain you didn't have any leaks I dare say you could seal the the ends up once it's screwed tight?

The possibility of needing a recharge at some point in the future has worried me, does anyone know how much it costs? I saw an ebay quote of £70, but being a little remote I'd guess it would be more for me.

richardc1983

Make sure Craig ur not installing the outdoor unit in the enlclosed space of the garage it wont work.

rothers8080

I'm not, the indoor unit is going in there so I don't have to keep buying gas bottles to heat the place while I work on my car

Once I'm finished with the vac pump + tools I suppose it could be possible to rent it out to anyone who needs it if we could work out a sensible way of doing it, ie work out how to send and return it.