Heat pump / inverter DIY

richardc1983

One thing to remember though Steve is that manufacturers state that the full capacity of the system is only output in high fan speed. For instance you have a 12000btu unit installed, the unit will only be capable of giving 12000btu if the fan speed is set to high. The lower the fan speed the lower the output of the unit due to lower air volumes. I am the same as you though, i do not run the fan speed on auto mode due to the annoyance of the noise of the air flow increasiing and decreasing. If i first get in from work and its cold I tend to turn to high fan speed until the unit cycles off after I switch back to low fan speed and it remains in low fan speed all the time. The unit is more than capable however of reaching set point on low fan speed at initial start up however it would take a little longer as the unit doesnt move as much air. I deliberatly asked for my units to be oversized so that I could run them in low fan speed and it would probably be running at the actual Heat/cooling load of the room anyway. We have 2 x 12000btu indoor units, i think heating and cooling load of the rooms are only about 10000btu anyway so basically the unit cools and heats my hallways and kitchen with the extra capacity its got. Its excellent really im so happy with it.

Outdoor noise levels are about the same 48db down to about 36db when the unit is only ticking over so to speak.

My flatmate however is annoyed because his room is situated down a hallway round a corner and the heat doesnt get that far down the hall so he is still using an electric heater on a night!!! Much to my disapproval due to the electric heater costing more to run than my a/c system and struggling to heat the room the heater is in!!!

Rusty boxes wise, im not sure, they are manufacturerd different now, i make sure I keep the outdoor unit clean and even use car polish stuff so water just runs off.

stevehead

We've pretty much got the same running methods Rich; like you I'll switch on high or even sweat-box 'Turbo' to get up to temp, then tick along on low the rest of the time.
With earlier technology, it used to be important to accuratly size the system to the space. This was because:
If the compressor is too small it won't provide enough heat
If the compressor is too big, it's forever cutting in and out with resulting inefficiencies, noise & wear. (Like your fridge, it was on or off)
But with AC Inverter Aircon it's best to oversize and run it well under max load. This way, the controller electronics looking after the compressor speed will keep it slow most of the time. There is less wear & noise too.

Rich... are you running off 3 pin plug, or directly into a spur? The reason I ask, is that I had mine put on plugs so I could put an energy monitor directly onto my heating system. Have you any stats for how much your's is costing to run?
I zero my Energy monitors on the first of each month, as I like to keep a tally of my heating KWh.
eg
Dec 1st - Dec 7th
Upstairs Unit 28.62 KWh
Downstairs Unit 33.77 KWh
Total 62.39 KWh

So on a bloody cold December week, with house occupied every day (work from home, wife off work) it's costing just under a quid a day on BG Click Energy 6 Tariff.
November was about 60p a day.

This week was expensive, huh? I put some of that down to my teenage daughter. I discovered that she'd come home from school frozen (insists on 'fashonable' ie inappropiate clothing) and just whacks the upstairs unit on 30 degrees flat out, then lies underneath it!

BTW I'm not trying to save energy at any cost; I've been reading in these forums about washing in cold water, wearing loads of wooly jumpers etc. My goal this year was to improve the comfort & lighting in my home AND slash my energy consumption.

Good to compare real experiences with you Rich, and if the OP would chip in with a progress report that would be interesting too.
Just off to Turtle Wax my heaters ha ha!

richardc1983

This is where its gonna be difficult to advise you how much its costing us. We have them connected into the main ring main for the power sockets. The problem being that we are also on a coin meter (£1) coins, and pay 15p per unit of electric at any time.

So per day if the units are on all day at 22C we can end up putting about £3 in of electric per day, possibly £4 if its really cold, this is obviously including our other electric usage, tvs, lighting etc which is all low energy. We pay a fortune for our electric our landlord is tight!

Here is the link to the outdoor unit specs so you can compare to yours, this will give the energy usage etc, prob not as efficient as the mitsi but still A rated and latest model from LG.

The model number is the FM25AH and the combination (indoor units) MV12AH which can be seen in the combination tables.

http://mylg.co.uk/data%20for%20site/multi%20f%202008%20outdoor.pdf

Pold

Just a quick responce regarding the "no need to vac the pipes" theme im seeing running through this thread.
Water boils under a vacuum its called "vacuum drying" you should never just connect any form of airconditioning equipment to refrigerant pipework that has been open to the air! any non-condensables in the pipe work air,water,water vapour etc.... will boil in the vacuum and be removed through the vac pump exhaust.
If you dont your asking for problems!
You should pressure test the pipe work with dry nitrogen and then vacuum dry the pipe work and hold it on a torr (a measure of vacuum) for at least 30 min so ensure no moisture and to ensure the pipe work is totally sealed.
Rant over

richardc1983

Pold you shouldnt be advising anyone on how to do it, they should be getting a fully qualified person in to do it.

stevehead

Just for info if you're reading this thread:

2 X Mitsubishi SRK20ZGX-S Split Systems
Supply & Install of Front Room and Upper Landing Units; 2 Outdoor Units
All internal & external work Trunked Pipework (neat)
Local AirCon firm charged £2400

Note that these units qualify for ECA
This allows you to claim back 100% of the entire cost against tax in 1 year
If you work from home, it's compelling stuff

rothers8080

I've managed to find someone local to come and leak test the system and vac the pipes before I turn it on.

It amazed me how hard it was to find someone who would do this, or to find someone who knew what these things even were. Most aircon engineers were confused why I had a unit at my house and said they only did commercial work. One of them even said I was wasting my time trying to heat my house with aircon units.

Anyway the kit was DIY and precharged / pre flared pipes. Just mounted it on the wall and put the pipes to the unit outside, the electrics came pre wired to a plug.

So I guess it's as close as you can get to DIY, it only needs leak testing and vacing, the pipes were sealed until you connected them, I'll post some photos and more information after this guy has been to leak test it tomorrow.

The only place it could leak would be from the flared pipes, apparently you can damage them by over tightening them so I've been pretty careful. I have a flare kit at hand should they be damaged though.

richardc1983

Craig im glad you have seeked proper advice. It will be interesting to see how your system looks when you have got it up and running.

A lot of air con engineers will make a loss of profit if they are not supplying and installing the system from start to finish, A large profit is made on the supply of the actual kit, they buy the units from a supplier and then they resell this onto you in the price of the install, they then take home a profit on the kit. For an engineer to come out and do small jobs on the diy systems they are not really making profit and they could be on another job elsewhere that is pulling them more money in.

It will be interesting to know what you think of your unit, let us know how u find them for noise, particulary the outdoor unit, it would be good to see a video of the outdoor unit in operation on the heating mode to see how loud it is.

Regards
RIch.

thechippy

Interesting thread!
My ch boiler has just failed and I've been quoted £3100 to have it sorted!!
A/C is my trade, so I'm now looking into binning the ch system and installing inverter heat pumps.
BTW, I'm quite happy to install customer supplied equipment, I can't see why some engineers have a problem with it. It must be noted though, the equipment supplied by the diy stores is not that good and you will REALLY struggle to obtain spares should it fail and tech support is non existant!

G

paceinternet

Why would you bin the central heating system?
Surely you would consider a heat pump with a heat exchanger, at least to compare with an air to air system?