Fitting my heat pump DIY

[eniacs]

Over the past month or so I've completed the DIY install of my heat pump. I enjoy a project and I've been looking at heat pumps since around 2010. I have tried to minimise costs, however some costs were much higher than i had planned.

 

Not sure really what this post is about, perhaps i just wanted to vent and no one around me understands.

 

Costs:
Radiators: £4k
Heat pump: £600 outdoor unit, £750 flow controller, £400 tank
Parts: £3k (estimated – includes pump, piping, insulation fixings etc) - this may be a conservative estimate. Copper and its fittings add up a lot!
 

Notes:

Piping – I followed manufacturers instructions and used 28mm for main piping. This has been an expensive faff as fittings/pipes and tools all seem hard to come by and aren’t stocked by local stockists. We needed a 28mm pipe bender and this had to be delivered from 120 miles away as no one local had one. Most fittings aren’t in stock locally so had to be next delivery.

 

Space considerations: The indoor unit is massive taking up a lot of inside space. We will build a wardrobe around it and use it to keep clothes dry etc, but in reality this is a loss of interior space.

 

Usability: The system itself is complicated (Mitsubishi) normal people will simply not understand it and either use it wrong or need help.

 

Now running the system is great, producing hot water/heating/cooling. No other system out there can do all these things.

I feel generally this system is underdeveloped, like a development model. The final product to be released after a few people have tried it.. The combi boilers available are small and produce everything a large house needs in the size of a kitchen cupboard. I don’t think the outdoor unit size is too important though, but the indoor space lost is not going to be practical for a lot of UK homes. Most of the kit could be smaller, the Mitsubishi FTC6 wiring centre has so many inputs and outputs, most of which wont be used and the ones that are used could have been in the outdoor unit.

 

How do others find their heat pumps?

 

 

[ProDave]

Can you clarify, are you talking about a split unit?  If so who did the Fgas connections and charging?  If a monoblock, what is this big indoor unit you talk about?  A hot water tank?

 

I did my own with a LG 5kW monoblock and found it easy from a plumbing point of view, with a Telford stainless heat pump hot water tank. The wiring a little harder as the unit lacked a few fundamental control inputs that I had to work around.

 

Complicated - yes.  the supplied control panel which is supposed to do all you want in terms of controling it and setting on / off times is WAY too complicated for the average person.  I regard that as just a means to enter parameters and check for faults etc.  For the "user" controls I grafted in a perfectly standard central heating programmer so you can set heating and hot water on off times using a standard interface just like if you were using a gas boiler.

 

One of the BIG problems holding back installers, and in particular deterring present installers of boilers, is the electrical controls are way more complicated and so different from one manufacturer to another.  What is needed is a simple standard like with a gas system boiler, "call for hot water"  and "call for heat" are all that is needed and presented in a standard form like gas boilers.  The Grant heat pumps are the only ones I have seen so far that achieve this.

 

From a plumbing point of view, a heat pump is just like a system boiler.  It heats water, just flow and return connections.  That bit is easy.

[JohnMo]

Well done, once you get your head in the right pace fairly straight forward. Mine has nothing in the house, not even the controller. Bit of a faff being outside while commissioning, but after that there is no real reason to change stuff.

 

The price of the odds and sods soon stack up.

 

1 hour ago, eniacs said:

Now running the system is great, producing hot water/heating/cooling. No other system out there can do all these things.

Not sure what you mean by this, as many systems can do all three. Mine does out the box.

 

45 minutes ago, ProDave said:

One of the BIG problems holding back installers, and in particular deterring present installers of boilers, is the electrical controls are way more complicated and so different from one manufacturer to another.  What is needed is a simple standard like with a gas system boiler, "call for hot water"  and "call for heat" are all that is needed and presented in a standard form like gas boilers.  The Grant heat pumps are the only ones I have seen so far that achieve this.

Think most ASHP are being controlled and function more like air-conditioning, as those manufacturers are the ones making most of them.

 

Think some systems do offer this (many manufacturers seem to over think stuff), mine has a connection for DHW sensor or a volt free contact from a thermostat, three port valve wiring, and heating is just a volt free contact and a volt free contact to switch between heating and cooling

[eniacs]

1 hour ago, ProDave said:

Can you clarify, are you talking about a split unit?  If so who did the Fgas connections and charging?  If a monoblock, what is this big indoor unit you talk about?  A hot water tank?

 

From a plumbing point of view, a heat pump is just like a system boiler.  It heats water, just flow and return connections.  That bit is easy.

 

Sorry, its a monoblock R32 mitsu unit.

 

I'd agree its simple enough, but the pipes are massive and take up a lot of space. This was for a 8.5kw unit, if i had to get the 11kw unit (i was originally going for this one) the primary pipework would have been 35mm. This just seems ludicrously large and somthing local plumbers just dont do. I asked 3 plumbers i know to borrow their 28mm pipe bender, all said theyve not needed one that size!

 

 

15 minutes ago, JohnMo said:

Not sure what you mean by this, as many systems can do all three. Mine does out the box.

 

 Ah i mean in terms of boilers etc, nothing else does heating/cooling/hot water in one box. I originally started this journey wanting air con in the house!

[S2D2]

4 hours ago, eniacs said:

Radiators: £4k

Ouch, designer or just sheer size/quantity?

[eniacs]

3 minutes ago, S2D2 said:

Ouch, designer or just sheer size/quantity?

Imported from italy... heating/cooling and good ratings and good quality. Got stung for VAT twice though and high delivery cost.

 

See here:

 

Theres photos of my units further down that page.

 

[S2D2]

3 minutes ago, eniacs said:

Imported from italy... heating/cooling and good ratings and good quality. Got stung for VAT twice though and high delivery cost.

 

See here:

 

Theres photos of my units further down that page.

 

Ah yes, that'll do it. I can see the attraction of small size and cooling capability, how is the noise?

[ProDave]

2 hours ago, eniacs said:

I'd agree its simple enough, but the pipes are massive and take up a lot of space. This was for a 8.5kw unit, if i had to get the 11kw unit (i was originally going for this one) the primary pipework would have been 35mm. This just seems ludicrously large and somthing local plumbers just dont do. I asked 3 plumbers i know to borrow their 28mm pipe bender, all said theyve not needed one that size!

 

I did mine in 22mm but had issues with water flow rate which I solved by fitting a second circulating pump.  I do have all my dad's old plumbing tools including his Hilmor pipe bender that has 15, 22 and 28mm formers, and (it is old) I still have the imperial formers for it.

 

You could have just done straight runs and soldered elbows to avoid bending?

[eniacs]

10 minutes ago, S2D2 said:

Ah yes, that'll do it. I can see the attraction of small size and cooling capability, how is the noise?

They have 2 speed settings, 1 is quiet, 1 is audible. But they also have an auto setting which i prefer, when the temp is low, the fan is fast and then slows a lot as it approaches the set point. Think this will be the best setting, i dont it being audible if its cold in the room.

 

 

3 minutes ago, ProDave said:

I did mine in 22mm but had issues with water flow rate which I solved by fitting a second circulating pump.  I do have all my dad's old plumbing tools including his Hilmor pipe bender that has 15, 22 and 28mm formers, and (it is old) I still have the imperial formers for it.

 

You could have just done straight runs and soldered elbows to avoid bending?

I used tectite copper push fit for most of it, with plastic push fit where necesary. The 28mm was all copper though and there were a couple places i couldnt use 90deg's.

 

God knows how much copper ive put in. Theres a small mountian of the old stuff to take to the scrapper!

[JohnMo]

3 minutes ago, ProDave said:

You could have just done straight runs and soldered elbows to avoid bending?

I used Tectite push fits, for the copper pipe - nice bend radius and you can pick them up from Toolstation or Screwfix. I also made use of Hep2O for the longer runs

 

4 minutes ago, ProDave said:

22mm but had issues with water flow rate which I solved by fitting a second circulating pum

My run to the cylinder is quite long and in 22mm (existing from gas boiler to UFH not used for UFH with heat pump), I also have a secondary pump installed in the return line and powered at the same time as the three way valve. Works a treat.

[sharpener]

6 hours ago, ProDave said:

Complicated - yes.  the supplied control panel which is supposed to do all you want in terms of controling it and setting on / off times is WAY too complicated for the average person.  I regard that as just a means to enter parameters and check for faults etc.  For the "user" controls I grafted in a perfectly standard central heating programmer so you can set heating and hot water on off times using a standard interface just like if you were using a gas boiler.

 

One of the BIG problems holding back installers, and in particular deterring present installers of boilers, is the electrical controls are way more complicated and so different from one manufacturer to another.  What is needed is a simple standard like with a gas system boiler, "call for hot water"  and "call for heat" are all that is needed and presented in a standard form like gas boilers.  The Grant heat pumps are the only ones I have seen so far that achieve this.

 

Yes, 100%

 

I have spent quite a few hours working out if/how to integrate my proposed Vaillant Arotherm Plus with my existing controls. Fortunately its standard interface box has a voltage-free call for hot water and defaults to heating. With the extension box (VR71) it will accept v/f contacts for three further zones e.g. (i) radiator circuit (ii) underfloor heating (iii) thermal store. So the electrical interface is fairly straightforward, the wrinkle is optimising whether this box is placed near the existing controls, or near the pumps and valves which will be on the other side of the room.

 

Fortunately there are 6 control cores to the hw tank location and another 6 to the remote underfloor manifold which should be sufficient, though both will need to be re-purposed somewhat. I have previously traced and documented all this when installing a wireless Honeywell Evohome zoning system, which I want to retain because of the usage patterns and shape of the house. So it is all basically do-able.

 

Also I plan to re-use the current dual channel timeswitch to control the charging and discharging of the thermal store.

 

On top of it all I have an 8-channel internet timer box which enables me to control the existing setup remotely. Still debating whether to keep this, it is long in the tooth but the installer has no experience of the Vaillant internet add-on beyond one webinar, and the app has not got a very good press on this Arotherm fb group. Maybe the answer is to keep it in service until the Vaillant product has bedded down and then add it to the system as a DIY enhancement.

 

If all this were simply left to a good heating electrician I imagine the result would be ditching everything that exists, pulling lots of multicore through the house, and making do with what the native Vaillant control system is capable of.

 

So far I have concentrated on getting an agreed pipework schematic, I sense there are further challenges to come!

 

[Lofty718]

I have a VR71 and Sensocomfort with my gas boiler, it's a very good bit of kit but quite complicated with many different settings that even the installer barely understood himself but I worked it all out for myself.

[JohnMo]

7 hours ago, sharpener said:

 

Yes, 100%

 

I have spent quite a few hours working out if/how to integrate my proposed Vaillant Arotherm Plus with my existing controls. Fortunately its standard interface box has a voltage-free call for hot water and defaults to heating. With the extension box (VR71) it will accept v/f contacts for three further zones e.g. (i) radiator circuit (ii) underfloor heating (iii) thermal store. So the electrical interface is fairly straightforward, the wrinkle is optimising whether this box is placed near the existing controls, or near the pumps and valves which will be on the other side of the room.

 

Fortunately there are 6 control cores to the hw tank location and another 6 to the remote underfloor manifold which should be sufficient, though both will need to be re-purposed somewhat. I have previously traced and documented all this when installing a wireless Honeywell Evohome zoning system, which I want to retain because of the usage patterns and shape of the house. So it is all basically do-able.

 

Also I plan to re-use the current dual channel timeswitch to control the charging and discharging of the thermal store.

 

On top of it all I have an 8-channel internet timer box which enables me to control the existing setup remotely. Still debating whether to keep this, it is long in the tooth but the installer has no experience of the Vaillant internet add-on beyond one webinar, and the app has not got a very good press on this Arotherm fb group. Maybe the answer is to keep it in service until the Vaillant product has bedded down and then add it to the system as a DIY enhancement.

 

If all this were simply left to a good heating electrician I imagine the result would be ditching everything that exists, pulling lots of multicore through the house, and making do with what the native Vaillant control system is capable of.

 

So far I have concentrated on getting an agreed pipework schematic, I sense there are further challenges to come!

 

Are you sure you need the install to be so complicated? Its complect just reading it, let alone installing and getting to work efficiently.

[sharpener]

6 hours ago, Lofty718 said:

I have a VR71 and Sensocomfort with my gas boiler, it's a very good bit of klt but quite complicated with many different settings that even the installer barely understood himself but I worked it all out for myself.

 

Have you found any decent documentation for the VR71 @Lofty718? By which I mean a description of what all the inputs and outputs are intended for and what the voltage levels are? Seems to be lacking, though I have reverse-engineered a version by looking at numerous schematics and Vaillant tell me my interpretation is correct as far as it goes.

 

The SensoComfort simulator on the web is quite good.

 

2 hours ago, JohnMo said:

Are you sure you need the install to be so complicated? Its complect just reading it, let alone installing and getting to work efficiently.

 

It is designed to be hierarchical in the following way (and commissioned in this order):

 

So at the bottom level is the HP and its native controls, this should work to give DHW, and plain WC heating if the frost stat on landing is turned up so as to create the demand. Zones and thermal store do nothing in this mode. I will get the installer to achieve just this level of functionality to begin with.

 

The thermal store comes next, the re-purposed external timer will control when it charges (e.g. 0500 - 0600 on Economy 7, and 1300 - 1600 from surplus PV or Octopus Cosy) and when it discharges (to feed bedroom radiators 0700 - 0830 and 2200 - 2330).

 

Then we have the Honeywell zone control system. If any zone is calling for heat it will turn on the Honeywell boiler relay wired in parallel with the frost stat so calling the HP on its two-wire voltage free heating input. Other than that it is electrically separate.

 

Lastly is the internet control box. By judicious use of the 4 normally closed and 4 normally open relays it will default to allowing all of the above to operate normally if it is powered down, is reset by a power outage, or fails. Two of its timers also do the night setback for the MVHR fan speed.

 

Edited November 7, 2023 by sharpener

[JohnMo]

18 minutes ago, sharpener said:

 

Have you found any decent documentation for the VR71 @Lofty718? By which I mean a description of what all the inputs and outputs are intended for and what the voltage levels are? Seems to be lacking, though I have reverse-engineered a version by looking at numerous schematics and Vaillant tell me my interpretation is correct as far as it goes.

 

The SensoComfort simulator on the web is quite good.

 

 

It is designed to be hierarchical in the following way (and commissioned in this order):

 

So at the bottom level is the HP and its native controls, this should work to give DHW, and plain WC heating if the frost stat on landing is turned up so as to create the demand. Zones and thermal store do nothing in this mode. I will get the installer to achieve just this level of functionality to begin with.

 

The thermal store comes next, the re-purposed external timer will control when it charges (e.g. 0500 - 0600 on Economy 7, and 1300 - 1600 from surplus PV or Octopus Cosy) and when it discharges (to feed bedroom radiators 0700 - 0830 and 2200 - 2330).

 

Then we have the Honeywell zone control system. If any zone is calling for heat it will turn on the Honeywell boiler relay wired in parallel with the frost stat so calling the HP on its two-wire voltage free heating input. Other than that it is electrically separate.

 

Lastly is the internet control box. By judicious use of the 4 normally closed and 4 normally open relays it will default to allowing all of the above to operate normally if it is powered down, is reset by a power outage, or fails. Two of its timers also do the night setback for the MVHR fan speed.

 

As I said, very complex. Found myself doing this sort of thing, when I first built the house, slowly undid it all when I started seeing the bills - KISS wins every time.

[TonyT]

Fit  storage heaters chargered via off peak cop 4 compared to standard peak electricity.  No moving parts, no maintenance easy to control now that’s KISS…

 

[JohnMo]

4 minutes ago, TonyT said:

off peak cop 4 compared to standard

Who are you with to that price. My E7 is 0.1516 per kWh.

[TonyT]

7.5p off peak with Octopus 

[Lofty718]

2 hours ago, sharpener said:

 

Have you found any decent documentation for the VR71 @Lofty718? By which I mean a description of what all the inputs and outputs are intended for and what the voltage levels are? Seems to be lacking, though I have reverse-engineered a version by looking at numerous schematics and Vaillant tell me my interpretation is correct as far as it goes.

 

The SensoComfort simulator on the web is quite good.

 

 

It is designed to be hierarchical in the following way (and commissioned in this order):

 

So at the bottom level is the HP and its native controls, this should work to give DHW, and plain WC heating if the frost stat on landing is turned up so as to create the demand. Zones and thermal store do nothing in this mode. I will get the installer to achieve just this level of functionality to begin with.

 

The thermal store comes next, the re-purposed external timer will control when it charges (e.g. 0500 - 0600 on Economy 7, and 1300 - 1600 from surplus PV or Octopus Cosy) and when it discharges (to feed bedroom radiators 0700 - 0830 and 2200 - 2330).

 

Then we have the Honeywell zone control system. If any zone is calling for heat it will turn on the Honeywell boiler relay wired in parallel with the frost stat so calling the HP on its two-wire voltage free heating input. Other than that it is electrically separate.

 

Lastly is the internet control box. By judicious use of the 4 normally closed and 4 normally open relays it will default to allowing all of the above to operate normally if it is powered down, is reset by a power outage, or fails. Two of its timers also do the night setback for the MVHR fan speed.

 

There is barely any documentation on the Vaillant wiring centres and like you I got my information from schematics/reading forums

 

With the VR71 it's a case of wiring your auxillary inputs into it, mine being UFH pump, radiator circuit pump and an electronic mixing valve (esbe)

 

Then the corresponding sensors need to be fitted to the pipework one for each zone, then another sensor before low loss header if you have one and also one sensor sits in the cylinder pocket and all of this combined with the outdoor weather sensor allows amazing control of your heat source.

 

 

Edited November 7, 2023 by Lofty718

[JoeBano]

On my own install, the hardest part was getting everything balanced Ufh radiators 4 port buffer (4 port buffer because my heat pump is oversized) but now it works great. I do most of my heating in the cheap periods using the low tariff mode which’s boosts my flow temperature super cheap and 21c  room temperature. 

[Lofty718]

48 minutes ago, JoeBano said:

On my own install, the hardest part was getting everything balanced Ufh radiators 4 port buffer (4 port buffer because my heat pump is oversized) but now it works great. I do most of my heating in the cheap periods using the low tariff mode which’s boosts my flow temperature super cheap and 21c  room temperature. 

Nice, low temperature heating is definitely the way forward. My system boiler runs at 36c flow temp and is keeping the house at 21.5 24/7

[sharpener]

1 hour ago, Lofty718 said:

There is barely any documentation on the Vaillant wiring centres and like you I got my information from schematics/reading forums

 

With the VR71 it's a case of wiring your auxillary inputs into it, mine being UFH pump, radiator circuit pump and an electronic mixing valve (esbe)

 

Then the corresponding sensors need to be fitted to the pipework one for each zone, then another sensor before low loss header if you have one and also one sensor sits in the cylinder pocket and all of this combined with the outdoor weather sensor allows amazing control of your heat source.

 

 

 

For anyone else looking this is the best I have been able to find, in a 700/2 controller manual online. VR71 pinout.pdf

 

Seems to have suffered a bit in translation, @Lofty718can you confirm that the demand inputs R6, R7, R8 are for external contacts that need to be closed for heat demand (as it would be for a conventional boiler)?

 

[JohnMo]

5 minutes ago, JoeBano said:

 I do most of my heating in the cheap periods using the low tariff mode which’s boosts my flow temperature super cheap and 21c  room temperature. 

I did try that, but the CoP hit not worth it. Have a big enough battery and PV when sun's out. So now just run a simple WC regime.

[Beelbeebub]

4 hours ago, TonyT said:

Fit  storage heaters chargered via off peak cop 4 compared to standard peak electricity.  No moving parts, no maintenance easy to control now that’s KISS…

 

Simplicity is about the only thing storage heaters have going for them. Everything else about them sucks.

 

I look after a few properties with them and nobody likes them. Expensive to run, hot in the mornings, cold in the evenings and god help you and your back if you have to change one.

[SteamyTea]

3 hours ago, Beelbeebub said:

Expensive to run, hot in the mornings, cold in the evenings

Only if sized and used incorrectly.

Mine, from 1987, are fine.

If my house had twice the heat load, I could just charge them up to a higher temperature and for a bit longer.

 

Like a heat pump system, they are not used like gas or oil fired central heating.

 

If people can't get them to work, then they need to read up on them and stop blaming the technology.