Air Source Heat Pumps

merlinonline

My dad lives in a housing association property, over the past 35+ years he has lived there he has gone from coal fired back burner (hot water only - no CH) to Solid fuel CH (which wasn't very efficient) to oil, the oil boiler was on its way out and the HA said they weren't replacing them.

Now the house is about 90 years old (I can hear someone shuddering and sucking air through their teeth already!), past few weeks it has external insulation (cladding) added (in fact it was noticeable how much warmer the living room was when that was added - before the oil boiler was taken out). apart from the main central heating pipes everything has now been replaced, even gained an extra radiator. The system is the Mitsubishi Electric Ecodan not sure what size but the unit is pretty big. Its being commissioned tomorrow.

From reading this thread, well some of it (too big to read tbh!) and some of the scare stories, first thing is if you have these systems fitted to an old house then the cladding is a must, to anyone thinking about fitting such a system then make sure you get it fitted correctly and commissioned plus maintained, buying cheap off ebay is going to end in tears. It won't be cheap but if it works well then you will get the benefits.

A lot of problems are caused because people who have had these fitted just don't understand how to use the system, its not a conventional heating system and can't be turned off and on at will like gas or oil.

I'm going to keep a close eye on this, the airing cupboard looks like a heating geeks dream!

lovesgshp

merlinonline wrote: »

My dad lives in a housing association property, over the past 35+ years he has lived there he has gone from coal fired back burner (hot water only - no CH) to Solid fuel CH (which wasn't very efficient) to oil, the oil boiler was on its way out and the HA said they weren't replacing them.

Now the house is about 90 years old (I can hear someone shuddering and sucking air through their teeth already!), past few weeks it has external insulation (cladding) added (in fact it was noticeable how much warmer the living room was when that was added - before the oil boiler was taken out). apart from the main central heating pipes everything has now been replaced, even gained an extra radiator. The system is the Mitsubishi Electric Ecodan not sure what size but the unit is pretty big. Its being commissioned tomorrow.

From reading this thread, well some of it (too big to read tbh!) and some of the scare stories, first thing is if you have these systems fitted to an old house then the cladding is a must, to anyone thinking about fitting such a system then make sure you get it fitted correctly and commissioned plus maintained, buying cheap off ebay is going to end in tears. It won't be cheap but if it works well then you will get the benefits.

A lot of problems are caused because people who have had these fitted just don't understand how to use the system, its not a conventional heating system and can't be turned off and on at will like gas or oil.

I'm going to keep a close eye on this, the airing cupboard looks like a heating geeks dream!

It is not just the user, it is usually the installer who has not got a clue.

albyota

@ bazz@rr

Hi, the Grant Aerona you have will automatically use a 3 kW electric boost element as follows

All Grant Aerona Heat Pumps contain a 3kW immersion element as a boost heat source. This element will energise under either one or two conditions :
1. When the external ambient air temperature drops between -5C and +5C. This figure is variable and adjustable at the ATC.
2. When the heat pump has not seen a temperature rise of 1oC or more in the Return water from the heating system, in a 20 minute period.
The cable sizing to the heat pump must include for this additional 3kW load.

If the system is struggling to get to 42 degrees in pretty mild conditions, I hate to think how it's likely to perform in the winter, Also, these units are not inverter driven, so the current draw is either on or off. We've never fitted any, but have removed a few.......!

Baz@rr

I've been playing around a bit tonight and here's what happened.

Came in and light on meter was blinking at 2 times a second. Nothing plugged in and no lights on, so all coming from heating pump.

I went up to the airing cupboard where all the controls are and both heating and hot water were showing as being on (set by timer). I switched these both to "off".

Came downstairs and meter was flashing at about 1 blink every 10-15 seconds. Pump unit out in the garden was silent.

About twenty minutes later I noticed light was blinking like mad again. Went outside and sure enough, pump was working away. Heating and hot water both set to off on the control panel, and I even turned the stat on the side of the storage cylinder right down. It gave a click around 30degrees.

Came downstairs, lights still blinking like crazy, pump still working away outside.

Just to check I flipped the main power switch to the pump off, then back on again. Pump didn't kick back in, and light on meter back to blinking once every 10-15 seconds (with lights on).

Maybe it's just that I need to get my head around how the system works. Why was it pumping when there were - as far as I could tell - no demands being made on the system? That's the bit I don't get.

Can someone explain to me how it's supposed to work? The pump heats the water in the cylinder upstairs, then uses that to heat the radiators and provide hot water - is that correct?

Baz@rr

albyota wrote: »

@ bazz@rr

Hi, the Grant Aerona you have will automatically use a 3 kW electric boost element as follows

All Grant Aerona Heat Pumps contain a 3kW immersion element as a boost heat source. This element will energise under either one or two conditions :
1. When the external ambient air temperature drops between -5C and +5C. This figure is variable and adjustable at the ATC.
2. When the heat pump has not seen a temperature rise of 1oC or more in the Return water from the heating system, in a 20 minute period.
The cable sizing to the heat pump must include for this additional 3kW load.

If the system is struggling to get to 42 degrees in pretty mild conditions, I hate to think how it's likely to perform in the winter, Also, these units are not inverter driven, so the current draw is either on or off. We've never fitted any, but have removed a few.......!

Well that's just fantastic - I live in the Highlands of Scotland and it's currently around 2C, so is that why it's constantly kicking in?? If so, should I just accept the fact that the system is going to be impossibly expensive to run? Any tips for saving costs?

Something else I noticed - I've switched the pump off at the main supply twice tonight and the meter has gone back to a much more sedate pace. However, each time - once after about twenty minutes, once after about 5, there has been a tiny dimming of the lights. When I then check the meter - sure enough, it's flashing wild and the pump is working away.

So is the pump coming on drawing so much power that it's actually causing the lights to dim for a fraction of a second. Can that be right?!

albyota

Yes, unfortunately, this will also be a frost protection setting, this is, IMO one of the worst designs of heat pump, I have Mitsubishi Ecodan, no boost heater, it is inverter driven.

I would be inclined to call the letting agent / landlord / builder and have them send an engineer round to make sure it is set up correctly, keep a log of meter readings, however, from my experience, Grant don't have many good heat pump engineers.

albyota

Are you saying that with the heat pump completely off, the lights dim?
is the bathroom UFH electric? And is this coming on?, have you used much hot water, taps? Shower? is the immersion heater coming on to recover?

Baz@rr

albyota wrote: »

Are you saying that with the heat pump completely off, the lights dim?
is the bathroom UFH electric? And is this coming on?, have you used much hot water, taps? Shower? is the immersion heater coming on to recover?

With the heating and hot water switched off at the control unit in the airing cupboard the lights dim ever so slightly and I know the pump outside has switched itself on - possibly to prevent frost, although the control unit out in the garage doesn't say it's in frost prevention mode.

The UFH in the bathrooms runs off the air pump system as far as I know, but the UFH has not been turned on. Nor have I used any hot water, other than when turning the tap on to test it's hot - it is, but not overly so, and only after running for a good 20-30 seconds.

Baz@rr

So... based on the usage over the past 38 hours or so I'm looking at approximately £250 a month on electricity before I switch on a single light bulb. And that's with heating and hot water switched off for about 12 hours of that.

Well. Isn't that marvelous?

albyota

That's why we don't install them, sorry.
how long is your rental contract?