UPDATED: Air Source Heat Pumps/Air Con - Full Info & Guide, is it cheaper to run than mains gas?

nande2000

John_Pierpoint wrote: »

Yes, but do we really know HOW and Exactly WHY and WHEN the "Immersun" upsets the PV Inverter. At the moment we know WERE and we think we know WHO (Immersun) is responsible.
From many years in systems analysis I know the really nasty ones to solve are where two manufacturers' equipment are both interacting to contribute to the problem, So could the problem be unique to the particular model of inverter?
If I was Immersun's ceo I would make sure this problem was fully explained PDQ. He/she would not want to feature in a thread like this
https://forums.moneysavingexpert.com/discussion/comment/43205962#Comment_43205962
or this:
https://forums.moneysavingexpert.com/discussion/2959648

In both cases the management appeared as candidates for bone head of the year.

Ive been through the loop with Fronius about the inverter, we've looked at the logs and I agree with them that the inverter is doing what it is supposed to do..i.e. if the grid voltage is outside of the specified limits it turns itself off. Given that the problem didnt occur prior to the install of the immersun and 4Eco are being open and honest about there being a problem and that the solution has been piloted and proven. I am hopeful the firmware upgrade will fix the issue.

Will report back after it has arrived and ive trialled it for a while.

Silent_Dancer

nande2000 wrote: »

Ive been through the loop with Fronius about the inverter, we've looked at the logs and I agree with them that the inverter is doing what it is supposed to do..i.e. if the grid voltage is outside of the specified limits it turns itself off. Given that the problem didnt occur prior to the install of the immersun and 4Eco are being open and honest about there being a problem and that the solution has been piloted and proven. I am hopeful the firmware upgrade will fix the issue.

Will report back after it has arrived and ive trialled it for a while.

My feel is that you are falsely blaming the Immersun. The challenge for the inverter is match voltage and frequency of the incoming mains (230V 50hZ at the right place in the cycle.) A lot of electrical equipment is quite sensitive to voltage spikes and troughs and out of cycle AC.

nande2000

The new version of the immersun from 4eco looks to have fixed the islanding I was having. The new version allows you to set a slower 'burst' rate. The best way I've heard it described is that the immersun is like a kettle that switches off and on continuously and very fast, seems if its too fast in a high impedance area the inverter doesn't like it.

nande2000 wrote: »

Ive been through the loop with Fronius about the inverter, we've looked at the logs and I agree with them that the inverter is doing what it is supposed to do..i.e. if the grid voltage is outside of the specified limits it turns itself off. Given that the problem didnt occur prior to the install of the immersun and 4Eco are being open and honest about there being a problem and that the solution has been piloted and proven. I am hopeful the firmware upgrade will fix the issue.

Will report back after it has arrived and ive trialled it for a while.

[Deleted User]

Largely irrelevant post but here goes...

My old man asked us what we paid in the last winter quarter for heating etc...?

Both houses are similar age/construction/size/rooms/20 miles apart in Scotland. Both with heating etc running regularly day.

His 'mains' gas bill for the winter quarter £450 + electricity say another £100ish = £550ish :eek:

Me, whole house consumption inc ASHP for same period £403

Take from that what you will.

Cheers

EDIT: Solar Immersion was not installed at that point and the solar pv hardly makes any contribution at that time of year.

asalih

Hi,

Sorry if I'm hijacking the thread - it seemed like a general purpose one.

I'm thinking of buying one a Mitsubishi inverter split system, but I can't believe the running costs can be so cheap and was wondering if anyone could help me with the calculations. Are there "hidden" power consumption figures I should be aware of?

Service Manual here:

webinder.mitsubishielectric.it/pdf/OBH623.pdf

Calculations so far:

Power input (see page 5) = 29 Watts = 0.029 kW
Electricity unit rate (per kWh)= 12.796*

24-hour running cost: (0.029 x 24) x 12.796 = 8.9 pence !

Monthly cost = 0.089 * 31 = £2.76 !

* I obtained a domestic rate (Electricity single rate) from British Gas just for illustration purposes from here:

britishgas.co.uk/products-and-services/gas-and-electricity/our-energy-tariffs/tariff-rates.html

Thanks,
Asal

Cardew

Welcome to the forum.

The(Italian) link doesn't open for me.

Certainly they use far more than 29 watts - is that just the fan consumption?

asalih

Thanks for getting back to me. Indeed, completely forgot to look for ratings for the outdoor unit!

With the outdoor unit, you've got separate figures for the main unit, compressor and fan. I'm not sure now how to do the calculations.

Here's dropbox links for both if you don't mind having a look (sorry as a newbie, can't post actual hyperlinks.. you'll have to copy and paste verbatim).

Indoor unit:

dropbox.com/s/ufzq76i1gwtqfq8/Indoor_Unit_MSZ-FH35VE_%20OBH623.pdf


Outdoor unit:

dropbox.com/s/usfqcja22s5c9zs/Outdoor_Unit_MUZ-FH2535VEH_OBH625.pdf

Cardew wrote: »

Welcome to the forum.

The(Italian) link doesn't open for me.

Certainly they use far more than 29 watts - is that just the fan consumption?

Cardew

Without going into the theory of Air to Air heat pumps, there is no set figure of consumption you can use.

The all important measurement of heating performance is the COP(coefficient of performance) e.g. with a COP of 3 you get an output of 3kWh heat for 1kWh input.

The Mitsubishi units quote a COP of 5.0 and 5.5 but as the outside temperature drops so does the COP - the performance curves demonstrate this well. Also critically the spec states this:

NOTE:

The above broken lines are for the heating operation without any
frost and defrost operation

Defrosting can be the 'killer' for heat pumps.

However there are plenty of people who state that air to air heat pumps give better performance than air to water heat pumps. However they have two major disadvantages.

1. You need another method to heat domestic hot water.

2. Rooms without an inside unit need the doors left open.

3. In the USA when properties are designed with aircon/heating in mind, they have ducting to each room.

asalih

Thanks for such a comprehensive answer, educating me in the process.

Cardew wrote: »

Without going into the theory of Air to Air heat pumps, there is no set figure of consumption you can use.

The all important measurement of heating performance is the COP(coefficient of performance) e.g. with a COP of 3 you get an output of 3kWh heat for 1kWh input.

The Mitsubishi units quote a COP of 5.0 and 5.5 but as the outside temperature drops so does the COP - the performance curves demonstrate this well. Also critically the spec states this:



Defrosting can be the 'killer' for heat pumps.

However there are plenty of people who state that air to air heat pumps give better performance than air to water heat pumps. However they have two major disadvantages.

1. You need another method to heat domestic hot water.

2. Rooms without an inside unit need the doors left open.

3. In the USA when properties are designed with aircon/heating in mind, they have ducting to each room.

John_Pierpoint

asalih wrote: »

Electricity unit rate (per kWh)= 12.796*

Does that price include the VAT ?

Check the temperature at which the headline CoP is calculated.

For some reason air source pumps tend to quote an "average" winter temperature, that is conveniently well above freezing.

Before you do anything check out the "airtightness" of your property and tghe "U" value of your walls roof and floor not to forget the double glazed windows. £1 spent on improved insulation should earn £10 in saved capital costs for an oversized heat pump.
It is a trickle technology designed with "heuristics" to run 24/7.
I have not even started to explain those two bits of technology as if you don't understand the terms, there is a learning curve ahead.
Anyone trying to sell you a heat pump without doing a full design fact find is a cowboy.
This is not like buying a gas boiler - just compare the outputs of a typical; heat pump and a typical gas boiler. You would probably need three phase electricity to run a gas boiler sized heat pump; as it is the installer should check with the local "DINO" to see if your single phase electricity supply is adequate, there might be £000s to pay to have it upgraded.
[Something to be said for doing it before the neighbours do, you get first mover advantage]

Thousands, who should have known better, have been conned in this thread:

https://forums.moneysavingexpert.com/discussion/2959648