ASHP/UVC/UFH Configuration

[LA3222]

Hi folks, 

 

I've read everything I can on here and have tried to blend all the drawings I came across into one. The sketch below is where I am at so far, if advice can be given as to whether I'm on the right track, if not why then that would be much appreciated.

 

TIA

 

 

[PeterW]

Pump ..? Should be one on the cold return to the ASHP. 
 

Buffer with coils - only a coil for either the UFH or the ASHP. Don’t need both. If buffering the UFH then you need the expansion on the UFH circuit. 

[LA3222]

9 hours ago, PeterW said:

Pump ..? Should be one on the cold return to the ASHP. 
 

Buffer with coils - only a coil for either the UFH or the ASHP. Don’t need both. If buffering the UFH then you need the expansion on the UFH circuit. 

Thanks for the steer.

 

When drawing version 1 I forgot about the fact I have two manifolds tapped onto the buffer vessel rather than a coil (as per previous discussion on multiple manifolds!).

 

Version 2 now attached, any feedback is much appreciated.

 

 

[PeterW]

Looks good to me. You will need some method of filling the UFH and buffer but another F&E will be easy to add. 
 

Immersions in all the tanks are a good idea - even the buffer. It can act as your secondary dump for excess PV too. 

[LA3222]

51 minutes ago, PeterW said:

Looks good to me. You will need some method of filling the UFH and buffer but another F&E will be easy to add. 
 

Immersions in all the tanks are a good idea - even the buffer. It can act as your secondary dump for excess PV too. 

Thanks Peter, F&E - fill & expansion? So make the expansion tank on the Buffer a fill loop aswell?

 

Good shout on the immersions in the buffer.

[PeterW]

Yep you need some way to fill the buffer and loops - don’t forget to add some inhibitor too. 

[Pete]

1 hour ago, LA3222 said:

Thanks Peter, F&E - fill & expansion? So make the expansion tank on the Buffer a fill loop aswell?

 

Good shout on the immersions in the buffer.

Many thanks for this info. Are you going onto the wiring as well? I know @PeterWmentioned a W plan but cannot find much info about it? TIA

[LA3222]

26 minutes ago, Pete said:

Many thanks for this info. Are you going onto the wiring as well? I know @PeterWmentioned a W plan but cannot find much info about it? TIA

I will be, just trying to work through it in baby steps so I understand what goes where/why and to make sure I don't miss anything.

[Pete]

9 hours ago, LA3222 said:

I will be, just trying to work through it in baby steps so I understand what goes where/why and to make sure I don't miss anything.

You take as many baby steps as you need, I am right behind you! 

[PeterW]

9 hours ago, Pete said:

Many thanks for this info. Are you going onto the wiring as well? I know @PeterWmentioned a W plan but cannot find much info about it? TIA

Decent site to understand all the “Plans”

 

https://www.flameport.com/electric/central_heating/heating_wiring_W_plan.cs4

[LA3222]

10 hours ago, PeterW said:

Yep you need some way to fill the buffer and loops - don’t forget to add some inhibitor too. 

Thanks for the feedback Peter.

 

So a bit of reading tells me that inhibitor goes into the UFH loops to stop bacteria etc. growing and potentially blocking pipes.

 

The loop which goes from ASHP --> UVC/Buffer is filled as you mentioned elsewhere:

On 10/09/2018 at 22:44, PeterW said:

As @ProDave says - you can use ordinary inhibitor based antifreeze which isn’t that expensive and the volume is about 15-20% to get the cover down to -10c. It’s only really an issue if the ASHP isn’t in use and the outdoor pipes freeze - it takes water a fair while to drop to freezing point if they are insulated with 15mm of nitrile rubber insulation (35c to -2c is 9 hours from memory) so this is only really needed if the heat pump is not on for a long cold period or the power fails. 

 

I plan to use a mix of decent insulation, an amount of inhibitor and also a timed frost programme on the heat pump to run the pump every couple of hours if the outside temperature is below zero. All those should resolve any issues. 

 

Now I want to try and understand things a bit better if you don't mind giving me a steer?:

 

Expansion Vessels on the UVC & Buffer - is this a standard detail due to those systems being a closed loop and pressurised? i.e the UFH loop which draws from the heated water in the buffer needs somewhere to expand into as it heats, the UVC is a 'closed' loop until a tap opens up to draw water from the tank.

 

The circles with an X through them - these are something I've merged into my drawing from elsewhere, what are these and their purpose? Valves of some description, to isolate parts of the system?

 

Are there any other components that should be included which i have failed to include which i should take into consideration?

 

Thank you

 

 

[Pete]

On 29/09/2020 at 08:01, LA3222 said:

Thanks for the steer.

 

When drawing version 1 I forgot about the fact I have two manifolds tapped onto the buffer vessel rather than a coil (as per previous discussion on multiple manifolds!).

 

Version 2 now attached, any feedback is much appreciated.

 

 

 

On 28/09/2020 at 22:01, PeterW said:

Pump ..? Should be one on the cold return to the ASHP. 
 

Buffer with coils - only a coil for either the UFH or the ASHP. Don’t need both. If buffering the UFH then you need the expansion on the UFH circuit. 

 

On 29/09/2020 at 08:22, PeterW said:

Looks good to me. You will need some method of filling the UFH and buffer but another F&E will be easy to add. 
 

Immersions in all the tanks are a good idea - even the buffer. It can act as your secondary dump for excess PV too. 

Just checking on this second drawing and your ref to buffer with coils etc as it still seems the same to my untrained eye!!TIA

[LA3222]

1 hour ago, Pete said:

 

 

Just checking on this second drawing and your ref to buffer with coils etc as it still seems the same to my untrained eye!!TIA

The first drawing has two coils for buffer tank, second has one. So the coil in the buffer tank is to circulate the ASHP water through thereby heating the buffer tank. The UFH then taps directly into the buffer, using the heated water within for the UFH.

 

I'm still working on all of this in the background. I think the fundamentals are there but I suspect a lot of component parts are missing. What I'm after is a 'complete' schematic rather than a 'general overview' which is what I think I have at the minute.  As I learn more I will post amendments to the drawing. Not sure why in the four yrs or so this forum has been running that a 'complete' schematic has yet to be posted up. I know that there will be nuances to each install but when you have a ASHP/UVC/UFH setup i can't believe they will be that different in terms of setup from build to build?‍♂️

[Pete]

25 minutes ago, LA3222 said:

The first drawing has two coils for buffer tank, second has one. So the coil in the buffer tank is to circulate the ASHP water through thereby heating the buffer tank. The UFH then taps directly into the buffer, using the heated water within for the UFH.

 

I'm still working on all of this in the background. I think the fundamentals are there but I suspect a lot of component parts are missing. What I'm after is a 'complete' schematic rather than a 'general overview' which is what I think I have at the minute.  As I learn more I will post amendments to the drawing. Not sure why in the four yrs or so this forum has been running that a 'complete' schematic has yet to be posted up. I know that there will be nuances to each install but when you have a ASHP/UVC/UFH setup i can't believe they will be that different in terms of setup from build to build?‍♂️

I have never been good at those spot the difference drawings!

[Benjseb]

You can also do the UFH buffer without a coil. It’s not really a buffer if it has a coil it’s more like a heat exchanger. 
 

if you keep the coil it means you only need glycol in the circuit from ASHP to buffer. Without you need glycol in the UFH too (I believe this is the usual setup)

 

The  issue with the coil is you need that circuit slightly hotter to transfer the heat the UFH circuit. Maybe 5c-10c hotter. Which introduces an inefficiency. Personally I’d just remove the coil and run it at a lower temp. 

 

 

[PeterW]

3 minutes ago, Benjseb said:

you keep the coil it means you only need glycol in the circuit from ASHP to buffer. Without you need glycol in the UFH too (I believe this is the usual setup)

It’s not glycol you need (usually used in a GSHP as a heat transfer media) it is just an antifreeze suitable for a central heating system that you need to use. The percentage is dependent on the capacity of the system but is usually 10-20%

[joe90]

46 minutes ago, Benjseb said:

Personally I’d just remove the coil and run it at a lower temp. 

my ASHP runs at 48’ (best temp for efficiency), buffer stat set at 30’. Buffer has coil fed from ASHP. UFH, runs at 24’, (blended down at manifold). Antifreeze in ASHP and inhibitor in UFH.  What inefficiency?.

[Benjseb]

2 minutes ago, joe90 said:

my ASHP runs at 48’ (best temp for efficiency), buffer stat set at 30’. Buffer has coil fed from ASHP. UFH, runs at 24’, (blended down at manifold). Antifreeze in ASHP and inhibitor in UFH.  What inefficiency?.

from my understanding the COP goes down with water temp. I’ve always been told/read that 35c would be much better over 45c for example. So therefore having the ASHP flow hotter than the final flow temp of the UFH means you’re running at a COP lower than needed 

 

where have you seen 48c is a sweet spot? That seems high to me. 

 

 

[Benjseb]

 

[joe90]

9 minutes ago, Benjseb said:

from my understanding the COP goes down with water temp. I’ve always been told/read that 35c would be much better over 45c for example. So therefore having the ASHP flow hotter than the final flow temp of the UFH means you’re running at a COP lower than needed 

 

where have you seen 48c is a sweet spot? That seems high to me. 

 

 

My ASHP can only be set to one temp and I need 48’ fir my DHW, My ASHP has never defrosted. I don’t have the ability to accurately measure my COP as I would be interested (if I could). ( @SteamyTea, as my tech support guy how could I do this?). I followed  @Jeremy Harris as I have the same ASHP as him, unfortunately he is not available to comment as he would know these things.

[SteamyTea]

25 minutes ago, joe90 said:

I don’t have the ability to accurately measure my COP as I would be interested (if I could

Think it depends on how accurate you need it.

The simple way is to put a heat meter on the output pipe (really just a flow meter and temperature sensor) and an electric energy meter on the input.

A cheaper way may be to put 4 temp sensors in. Two for the air temperature either side of the radiator, one on the flow out of the HP and another on the return pipe. That would give extra useful information about how your UFH is performing.

That is basically what we have done to your MVHR (I wonder if it is still logging as been left untouched for about 18 months now).

A quick Google to refresh my memory shows that:

 

CoP(heating) = T(h) / T(h) - T(c) 

 

And

 

CoP (cooling) = T(c) / T(h) - T(c)

 

So maybe only 3 sensors, which is easy to set up. May be worth putting a fan and pump sensors on so that time of day usage is logger.  That can be correlated to the electrical energy logger I put in.

And then some RH sensors just for a giggle.

 

Edited October 18, 2020 by SteamyTea

[ProDave]

My LG ASHP has separate set temperatures for DHW and heating.  I run the ASHP in heating mode at the UFH temperature so there is no "loss" and it heats the water no hotter than the UFH requires.  It appears not all ASHP's allow you to set different temperatures.

[SuperJohnG]

On 29/09/2020 at 08:01, LA3222 said:

as per previous discussion on multiple manifolds!

@LA3222 can you point me in the direction of this discussion/thread? 

 

Typical - found it. 

 

For anyone else : 

 

Edited October 27, 2020 by SuperJohnG
Immediately found what I was looking for after asking...

[SuperJohnG]

I just realised I jad even commented in that other thread. ?

 

I thought I'd add some more relevant info here which will help close the loop on a few items, saves others asking the questions 

 

 

[LA3222]

Well, I have started to focus my attention on the plumbing side of the build now. After a fair bit or reading and looking at other layouts etc. I have come up with an updated version, basically an amalgamation of everything I've come across so far.

 

A few queries I still have:

 

Is the filter supposed to go on the cold return?

Should there be an air vent on the primary circuit somewhere?

Should the PRV be there? The drawing from an Ecodan manual shows one, yet elsewhere I read not to put one in?

Does it matter what order the components go in i.e. of the cold return loop?

Flow sensor - is that needed? I came across a couple of drawings which showed one.

 

Any feedback would be appreciated.

 

TIA