Grant/ Aerona ASHP expensive...

[JeffGiraf]

Hi all

 

I live in a rented old stone farmhouse in mid Scotland.  House is probably 240m2 or so. There is a fairly new ( fitted last March) ashp retrofitted to old UFH downstairs and undersized radiators upstairs ( though a new towel rail was fitted in the bathroom). Landlord (I know her!) did minimum cost install!

 

But the attic has extra insulation now ( but also coombs, which loose heat) and the out of use chimneys are capped and insulated with wool plugs.

We have also taped all the doors and have thick curtains and lovely old wood shutters.

 

The heating seems rather expensive. It used an average of 1.6kw per hour over the last 28.25 hours (we have a separate meter for the heat pump). For that the rooms stay around 16degC. Thank goodness for the woodburner.

 

Tank and everything, including the "remote" controller are in a dark shed sandwiched between our house and landlords so I have to sit on a wee fishing stool to monitor! It also means it thinks the temp in the shed is room temperature! Pipes in shed are insulated but not amazingly (normal grey foam insulation - not taped or glued, cable tied at some points). Tank is uninsulated beyond the way it comes, (I plan to get a jacket) but at the moment we are mostly using kettles on the fire for hot water and the immersion for an occasional bath rather than keeping water hot as the heating alone is expensive!

 

I have looked at the WC settings:

 

2100  0

2102  50 degC 

2103  35 degC

2104  -4 degC

2105  20degC

 

Outside temp around 2- -2degC daytime at present and colder at night. 

 

Monitor Display Readings a few days were as follows:

 

00  circulating h2o return temp 44degC

( went up from 38 degC as I watched)

01  Compressor op freq. 0hz

02  Discharge temp 88deg C

( I watched this climb from 30 deg C to 88 over about 3 or 4 mins)

03  power consumption value 100w

04  fan control of rotations 0

05  Defrost temp 2degC

06. Outdoor air temp 2degC

07. H2O pump contol no of rotations 3300rpm

08. Suction temp 4degC 

( what is this?)

09. Circulating h2o flow temp went from 39degC to 46degC

 

These were taken as I had previously turned the 50degC high temp down to 45degC but we were all freezing so I put it back up! 

 

I looked through all the installer level setting ( installer hadnt noted them in the handbook but I have!) and apart from 2102 and 2103 they are all at default.

 

For some reason the temperature gauge on the manifold flow pipe reads consistently at around 30-33degC. There is a mixer valve but it is set up at 55degC above the temp of the water from the heat pump. 

 

Any suggestions on how to make it cost less/more efficient would be much appreciated! Thanks

[JohnMo]

First complain to landlord or their agent, they are responsible to fix it and provide you heating that works.

 

Start looking for a better rental property?

[ProDave]

17 minutes ago, JeffGiraf said:

The heating seems rather expensive. It used an average of 1.6kw per hour over the last 28.25 hours (

So the ASHP is consuming 1.6kW to heat the house, assuming a COP of 3, that will translate to 4.8kW of heat delivered to the house.

 

It is very cold at the moment.  Our very well insulated 150 square metre house needs about 1.5kW of heat at the present sub zero average outside temperature.  So your house is larger, older and no doubt less well insulated, so 4.8kW of heat does not seem at all unreasonable.  Don't expect to reduce that significantly other than as above move to a smaller much better insulated house.

 

21 minutes ago, JeffGiraf said:

02  Discharge temp 88deg C

What exactly does that mean?  surely not the heat pump is set to heat water to 88 degrees?

 

22 minutes ago, JeffGiraf said:

Tank is uninsulated beyond the way it comes

Sounds very like it does not have the right sort of hot water tank for a heat pump.  Not much you cn do there as the system is not your to make alterations to.

 

It sounds like your expectations of the property are not matching reality, and as above again, all you can do is move to a better property.

[Nickfromwales]

Exactly the type of property that should never have had an ASHP installed on to.

 

So many useless tossers happy to take the money and say nothing.

 

Whats the EPC? 

[Nickfromwales]

25 minutes ago, JeffGiraf said:

We have also taped all the doors

Not how to live, but I’ve had to do similar in cheap rentals when me and the missus moved in together 30 odd years ago.

 

Laws / regs / acceptable minimum standards have changed now, so this just shouldn’t be happening.

 

16°C is terrible, they keep prisons warmer than that. 

[JeffGiraf]

First off important typo:

 

House is about 140m2 or so not 240m2! 

 

So that makes it more rubbish! Unfortunately any affordable rental housing is like hens teeth in rural scotland so we make do! I have been talking to thw landlord, but the installers are crap so I was trying to go in a little forearmed with kmowledge!

 

@Nickfromwales House EPC is C at 75 so not the worst but not the best.

 

By taping the doors I meant adding insulation tape not taping them up!

 

And yes ashp was done on a grant no surprise!

 

 

@ProDavewhat data do I need to calcate the COP? I don't really understand how its done?

 

I didnt know what discharge temp was either but found this: https://www.sciencedirect.com/topics/engineering/discharge-temperature guess 88 is ok then.

 

It is a Grant Aerona tank. I meant no extra jacket or anything.

 

The living room with the burner in it stays at around 17-18degC even overnight with the door to the rest of the house open. 

 

Why would the temp gauge at the manifold read around 15degC lower than the flow temp?

Edited 14 hours ago by JeffGiraf

[JeffGiraf]

Thanks for your replies so far!

[jamesdiyer]

I live in a big stone house in equally cold environment. We are doing around 2kw electric input currently at 2C. However we are warm at 20C inside. Contrary to what some people think, it can work very well with the right emittors. 

 

If you're flow temps are high but you're not warm, I'd say you have an emitter issue - emitters too small.  You need to get a grip on the UFH and why it's not working well - I'd say the landlord should be paying for someone to look at it. It sounds like the whole thing is a mess and needs to be dealt with properly. 

Edited 9 hours ago by jamesdiyer

[JohnMo]

9 hours ago, JeffGiraf said:

Grant Aerona tank.

It will not need an additional jacket, keep your money in your pocket. The what steel is just a shell protector with insulation side.

 

9 hours ago, JeffGiraf said:

Why would the temp gauge at the manifold read around 15degC lower than the flow temp?

Mixer on the UFH, it's mixing the flow temp down to limit floor output and protect the floor. It will have a temp control knob,if you increase that the flow temp through the floor increases. The basic mixer just work on a ratio control, it's assuming 70 Deg hot water from a boiler, if you can turn it up do so. Adding even a couple degrees to flow temp will have a big effect on room temp (after 24 hrs)

 

Other thing are you running the heating on all the time or an on off time cycle?