Another ASHP plumbing schematic!

[JulianB]

Evening all,

 

Was in two minds whether to hijack another thread on the subject, but in the end I thought it may be better to post a fresh. As with many others, I'm honing in on my plumbing schematic, the bulk of which I hope to be completing myself (with the exception of the G3 sign off). I'm in the process of purchasing a Panansoic TCAP ASHP, which comes with a circulation pump, expansion vessel, strainer and flow setters in built in the monoblock unit. I was initially tempted to go down the route of a pre-plumbed cylinder, however due to me not having a great deal of space and hoping to fit it all under the stairs, opted for greater flexibility with individual components. 

 

The runs from UVC to both ASHP and bathrooms is under 5 metres (the house is pretty compact!), and sit on the ground floor as the house is 'upside down'. We expect quite a bit of solar gain with two glazed gable ends (1st floor), and hence are going down the 'JHarris' route of pumping the UFH to even out the house for the majority of the time (do people run these 24/7?).

 

I've adapted what started off as the schematic on the Panasonic installation manual. It is far from pretty, apologies in advance! Panasonic advise on a 50L buffer tank however don't really mention whether this should be direct or indirect. I presume if this is indirect, an additional expansion vessel would be needed? Also, would the general recommendation be for the UFH side to be connected to the coil end of the buffer tank? I haven't placed a ASHP by pass, but have read these are recommended and should be as far away from the HP ? Also I've noted that the 3 way valve might not be the most popular choice!

 

Any comments / advice would be greatly appreciated

 

Thanks!

 

 

 

 

UFHV2.pdf

[Pete]

I fitted my Panasonic ASHP before xmas using the above diagram. I fitted an expansion vessel due to the size of my ufh system. The buffer tank if supplied by Panasonic does not have a coil inside, it is just a tank. My diverter valve is a two way, comes in from the heat pump and either goes to HW or UFH so pretty basic but works fine.

[Hobbiniho]

Yeh the panasonic tank is just to add volume to the system to stop the heat pump short cycling, you will need an expansion tank on your heating system as you dont currently have one shown. This expansion tank usually also has the fill loop connection aswell so will be connected to the "cold" side.

 

You also have your cold water feed to the house shown wrong, the balanced cold for the house should come off the bottom of the "black PRV" and not be connected to the tank feed

Edited February 13, 2021 by Hobbiniho
Adding info

[JulianB]

10 hours ago, Pete said:

I fitted my Panasonic ASHP before xmas using the above diagram. I fitted an expansion vessel due to the size of my ufh system. The buffer tank if supplied by Panasonic does not have a coil inside, it is just a tank. My diverter valve is a two way, comes in from the heat pump and either goes to HW or UFH so pretty basic but works fine.

 

Thanks for that Pete! Do you have any photos of the install by any chance? Did you go 28mm copper from the HP or plastic pipe, and did you opt for glycol or water + inhibitor seeing as you had quite a volume of fluid in the buffer tank + UFH?

 

4 hours ago, Hobbiniho said:

Yeh the panasonic tank is just to add volume to the system to stop the heat pump short cycling, you will need an expansion tank on your heating system as you dont currently have one shown. This expansion tank usually also has the fill loop connection aswell so will be connected to the "cold" side.

 

You also have your cold water feed to the house shown wrong, the balanced cold for the house should come off the bottom of the "black PRV" and not be connected to the tank feed

 

Thanks for pointing that out! Hopefully the revised schematic below should now look a bit better...I've put the filling loop on both expansion vessels and connected the heating system expansion vessel on the return side as I figured it would be more efficient connecting to the lower temperature side...thoughts? 

 

Would there be anything else that I'm missing...how about drain points and shut valves, am I lacking any trivial ones? I'm trying to keep it as 'lite' and simple as possible...I've seen some schematics with double check valves, are these really needed?

 

UFHv3.pdf

[PeterW]

Not sure why you need an expansion as your first post says the heat pump has one internally ..??

 

You need about 7-10% system capacity as expansion so will depend on UFH loops etc as to whether you need more than the inbuilt one. 

[JulianB]

13 minutes ago, PeterW said:

Not sure why you need an expansion as your first post says the heat pump has one internally ..??

 

You need about 7-10% system capacity as expansion so will depend on UFH loops etc as to whether you need more than the inbuilt one. 

 

That is a good point. My UFH volume is ~97L, plus the 50L buffer...haven't found anything online to confirm the size of the internal expansion vessel. Will ask the supplier on Monday...fingers crossed

 

Thanks!

[Pete]

40 minutes ago, JulianB said:

 

Thanks for that Pete! Do you have any photos of the install by any chance? Did you go 28mm copper from the HP or plastic pipe, and did you opt for glycol or water + inhibitor seeing as you had quite a volume of fluid in the buffer tank + UFH?

 

 

Thanks for pointing that out! Hopefully the revised schematic below should now look a bit better...I've put the filling loop on both expansion vessels and connected the heating system expansion vessel on the return side as I figured it would be more efficient connecting to the lower temperature side...thoughts? 

 

Would there be anything else that I'm missing...how about drain points and shut valves, am I lacking any trivial ones? I'm trying to keep it as 'lite' and simple as possible...I've seen some schematics with double check valves, are these really needed?

 

UFHv3.pdf 299.8 kB · 0 downloads

I used 28mm copper from HP to isol valves just inside the house and then 28mm Hep2o to the plant room and then 28mm copper in the plant room. I used glycol as it came with the system I purchased. I added another exp vessel as they do not cost much and just removed any doubt. 

The cold feed (HW) to the tank has the return leg for the heating side directly above it so we just fitted a filling loop there with check valve to make things easier.

[SteamyTea]

3 minutes ago, Pete said:

I used 28mm copper from HP to isol valves just inside the house

Our old mate @Jeremy Harris did that and found there was a lot of noise transmission.  He RTDM and found it should be fitted with 1.5m flexible pipework.

[Pete]

Sorry, the kit I bought came with two 1metre flexi pipes as I had read about the vibration problems. To be honest the pump is so quiet I am not sure there would be a problem but better to be safe than sorry!

[JulianB]

On ‎13‎/‎02‎/‎2021 at 21:45, Pete said:

I used 28mm copper from HP to isol valves just inside the house and then 28mm Hep2o to the plant room and then 28mm copper in the plant room. I used glycol as it came with the system I purchased. I added another exp vessel as they do not cost much and just removed any doubt. 

The cold feed (HW) to the tank has the return leg for the heating side directly above it so we just fitted a filling loop there with check valve to make things easier.

 

Thanks; A filling loop near the filter (item 2) on my diagram, prior to my drain cock? Is this filling loop over and above the 2 on the expansion vessels? Also could I ask what UVC you went for?

 

On ‎13‎/‎02‎/‎2021 at 21:50, SteamyTea said:

Our old mate @Jeremy Harris did that and found there was a lot of noise transmission.  He RTDM and found it should be fitted with 1.5m flexible pipework.

 

Good point, thanks! I recall reading Jeremy's blog re. the noise transmission without the flexible pipework sections; Will have to make it a point to rememder this one! Whilst on the subject of Jeremy's blog, I can't seem to access it anymore, has it gone offline?

 

With regards to the electronic shut off valves when running the pumps solely to even out slab temp, could I ask what logic / controllers people are using. I can see the basic principle of shutting off the return leg to force the UFH pump to draw from the return legs of the UFH manifold, however I presume this 'mode' / state of control needs to be aware of when there is a call for heat in order to reopen the return leg? Also would there be benefit in positioning the electronic shut valve further upstream on the return leg from the buffer to HP in order to circulate a greater volume of fluid? I could see this being a potential benefit when trying to kerb solar gain which might become an issue, however am not sure if a single electronic shut valve would create any conflict between the two UFH manifolds?

[SteamyTea]

13 minutes ago, JulianB said:

has it gone offline

Yes, as has Jeremy

 

14 minutes ago, JulianB said:

could I ask what logic / controllers people are using

Raspberry Pi's seem popular.

[JulianB]

41 minutes ago, SteamyTea said:

Yes, as has Jeremy

 

Raspberry Pi's seem popular.

 

Oh dear, hopefully all is alright on his end?

 

I'm not sure how I feel about integrating a Raspberry Pi into the system - part of me would like to keep things as simple as possible and whilst I haven't had first hand experience with Pi's, I do wonder if you might get the occasional niggling issue? My initial thoughts were to somehow intercept the call for heating from the HP / thermosat, and drive two relays which would in turn be connected to a secondary power supply to the UFH pump and the electornic shut valve. When there is no call for heating, the two relays will be NC, i.e. shut valve closed, together with a 'complete' secondary supply to the UFH circulation pump, which would be on a simple timer to ultimately dicatate when it receives supply. When there is a call for heating, both relays would open, and normal system operation would resume (regardless of the state of the secondary supply timer). What I haven't investigated is the feasability in terms of finding a suitable 'call for heat' signal which would drive the relays, and whether running the secondary power supply to the UFH pumps would cause any adverse affects through it's primary wiring system. Thoughts?

[SteamyTea]

2 minutes ago, JulianB said:

I'm not sure how I feel about integrating a Raspberry Pi into the system

Others have done the work.

https://www.electromaker.io/blog/article/9-best-raspberry-pi-smart-home-software-options

 

But I like to keep things as simple as possible.

[Pete]

1 hour ago, JulianB said:

 

Thanks; A filling loop near the filter (item 2) on my diagram, prior to my drain cock? Is this filling loop over and above the 2 on the expansion vessels? Also could I ask what UVC you went for?

 

 

Good point, thanks! I recall reading Jeremy's blog re. the noise transmission without the flexible pipework sections; Will have to make it a point to rememder this one! Whilst on the subject of Jeremy's blog, I can't seem to access it anymore, has it gone offline?

 

With regards to the electronic shut off valves when running the pumps solely to even out slab temp, could I ask what logic / controllers people are using. I can see the basic principle of shutting off the return leg to force the UFH pump to draw from the return legs of the UFH manifold, however I presume this 'mode' / state of control needs to be aware of when there is a call for heat in order to reopen the return leg? Also would there be benefit in positioning the electronic shut valve further upstream on the return leg from the buffer to HP in order to circulate a greater volume of fluid? I could see this being a potential benefit when trying to kerb solar gain which might become an issue, however am not sure if a single electronic shut valve would create any conflict between the two UFH manifolds?

Thanks; A filling loop near the filter (item 2) on my diagram, prior to my drain cock? Is this filling loop over and above the 2 on the expansion vessels? Also could I ask what UVC you went for?

Yes, a filling loop near the drain cock. You do not need anymore filling loops. I went with the Panasonic cylinder as it came in the kit I purchased.

[JulianB]

22 hours ago, SteamyTea said:

Others have done the work.

https://www.electromaker.io/blog/article/9-best-raspberry-pi-smart-home-software-options

 

But I like to keep things as simple as possible.

 

Thanks for that! I shall have a good read through!

 

22 hours ago, Pete said:

Thanks; A filling loop near the filter (item 2) on my diagram, prior to my drain cock? Is this filling loop over and above the 2 on the expansion vessels? Also could I ask what UVC you went for?

Yes, a filling loop near the drain cock. You do not need anymore filling loops. I went with the Panasonic cylinder as it came in the kit I purchased.

 

 

Good point re. only one filling point (DOH!). I have removed the one onUFHv4.pdf the DHW expansion vessel as presumably this fills from the main supply feeding into the PRV. Hopefully I'm just about there now! 

 

[Triassic]

You mentioned the volume of the UGH pipes,

 

Out of interest, what size is the house, number of bathrooms etc?

[JulianB]

3 hours ago, Triassic said:

You mentioned the volume of the UGH pipes,

 

Out of interest, what size is the house, number of bathrooms etc?

 

House is ~130m^2 in total, with 2 bathrooms and 1 WC. The 97L I quoted was off the UFH supplier's system.

[JulianB]

Morning All,

 

I've been having a good read through the Panasonic TCAP manual, together with the SALUS RF wiring centre / thermostats and have noticed cooling mode functionality, which activates the UFH pumps together with manifold actuators without calling for heat. The switching between heating and cooling relies on a simple no voltage changeover switch in the wiring centre , and thermostats are able to store set points for both heating and cooling mode simultaneously. I'm wondering whether this functionality makes the JHarris re-circulation mode pretty straight forward. I've emailled Salus to confirm compatibility with my intended use and will report back on the outcome, however it might be a hopeful solution at avoiding a separate home automation control system. 

 

In my attempt to keep things as simple as possible, my thoughts have now turned to the electronic shut off valves. Specifically, their removal... Am I right in thinking that if I do switch on the UFH pumps / manifold actuators without any shut valves present, the pumps would potentially 'suck' from both the return leg of the UFH manifold, and also the buffer tank (which I imagine is the path of least resistance?). Seeing as the pumps are also technically 'pushing' the flow into the 'flow' side of the UFH manifold, wouldn't that ensure that I would still be circulating the fluid through the UFH loops, as there is no other path it could choose? If this is the case, would this be a preferred option, as you are incorporating the buffer tank into your 'circulation' mode, and hence have a greater volume of fluid from which to manage any potential over heating risk etc?

 

 

[PeterW]

@JulianB are you expecting to run the ASHP in cooling mode also..? Not clear from your description / diagram..?

[JulianB]

29 minutes ago, PeterW said:

@JulianB are you expecting to run the ASHP in cooling mode also..? Not clear from your description / diagram..?

 

Hi Peter,

 

My original intention was to not run cooling mode on the ASHP, and solely rely on shifting the heat around the house to combat any overheating risks. I imagine after once we have our first summer in the house we'll have a good idea if that alone is enough.

[PeterW]

Zone valve on the inlet side then is what you need (and would be good practice anyway)

[JulianB]

2 minutes ago, PeterW said:

Zone valve on the inlet side then is what you need (and would be good practice anyway)

 

Thanks! What were your thoughts on the flow path if a zone valve wasn't present on either inlet or outlet and the pumps were fired up? Would the UFH loops still circulate?

[Nickfromwales]

Unless the buffer tank is a 2 tapping version ( series ) then you'll need likely need a secondary pump between it and the 2 UFH manifolds for primary circulation. A 2-port zone valve to each manifold would be 'the norm' as the secondary pump would push past the TMV > manifold pump and into the loops when one calls and the other doesn't.

15 minutes ago, JulianB said:

Would the UFH loops still circulate?

If there is a manifold pump, then you will always get circulation through the UFH loops, what is not guaranteed ( dependant on the topology and plumbing layout ) is circulation between the buffer tank and the manifolds. Also, you should really be diverting away from the buffer for cooling or you could have a big condensation 'bomb'. Lots of insulation could mitigate against that, but, for simplicity, you could just parallel a 2 pipe buffer across flow and return and toggle that in / out for heat / cool with a 2 port zone valve. At that stage the requisite for the secondary pump may be done away with, as long as there re automatic bypass valves at the flow and return of each UFH manifold ( at the very end of the supply pipework and immediately prior to any control valve / TMV / other ).

It's a tricky balance as the flow rte for the ASHP primary pump needs to be as open as possible to maintain the required rates, so a 4 pipe buffer is good for that, so you could toggle that in / out with a pair of 3 port diverter valves ( not mid-position valves ).

The above drawing will not work as is IMO, unless the buffer and manifolds are immediately next to each other, and then its a bit tricky to say as there are 2 manifolds. At the very least here, you should have anti-gravity ( single check or swing valve ) at the flow of each manifold to stop the 'sucking back' you refer to.

A few bugs left to work out here I'm afraid.

[JulianB]

On 05/04/2021 at 09:33, Nickfromwales said:

Unless the buffer tank is a 2 tapping version ( series ) then you'll need likely need a secondary pump between it and the 2 UFH manifolds for primary circulation. A 2-port zone valve to each manifold would be 'the norm' as the secondary pump would push past the TMV > manifold pump and into the loops when one calls and the other doesn't.

If there is a manifold pump, then you will always get circulation through the UFH loops, what is not guaranteed ( dependant on the topology and plumbing layout ) is circulation between the buffer tank and the manifolds. Also, you should really be diverting away from the buffer for cooling or you could have a big condensation 'bomb'. Lots of insulation could mitigate against that, but, for simplicity, you could just parallel a 2 pipe buffer across flow and return and toggle that in / out for heat / cool with a 2 port zone valve. At that stage the requisite for the secondary pump may be done away with, as long as there re automatic bypass valves at the flow and return of each UFH manifold ( at the very end of the supply pipework and immediately prior to any control valve / TMV / other ).

It's a tricky balance as the flow rte for the ASHP primary pump needs to be as open as possible to maintain the required rates, so a 4 pipe buffer is good for that, so you could toggle that in / out with a pair of 3 port diverter valves ( not mid-position valves ).

The above drawing will not work as is IMO, unless the buffer and manifolds are immediately next to each other, and then its a bit tricky to say as there are 2 manifolds. At the very least here, you should have anti-gravity ( single check or swing valve ) at the flow of each manifold to stop the 'sucking back' you refer to.

A few bugs left to work out here I'm afraid.

 

Morning Nick,

 

Thanks for the reply! I’ve re-read your post a few times now to let it settle in, but I don’t think I’m fully there yet with my understanding (pardon my ignorance!). Current grey areas:

1. What is a 2 tapping version – does this imply single inlet and outlet off the tank, rather than the Panasonic supplied 2 inlet / 2 outlet version that I have bought (PAW-BTANK50L)
2. Secondary pump – if my understanding is correct, this is only needed in this alternative ‘circulation mode’ when wanting to even out floor temps, and hence the inbuilt pump in the ASHP would not play any part. Would the risk of not having this secondary pump be that I couldn’t guarantee circulation between buffer tank and UFH manifolds? Would there be any other risks? I’m not sure what size an additional 2 pipe buffer would be, but I am very tight on packaging under the stairs unfortunately…would there be any benefit in running a simple bypass across the flow and return buffer tank with a 3 way switch (non-Mid switch) which I’ve temporarily drawn on my cobbled together schematic?
3. Good point re. condensation bomb – at present I’m not planning to run the ASHP in cooling mode at any stage, but part of me would want to future proof the system in the event things get a lot hotter than I expected? Part of me wants – would a by-pass in parallel with the buffer tank potentially work, or would the ASHP complain about flow rates given that I’ve removed that hydraulic separation between ASHP and my UFH system? I’m expected my UFH volume to be in the order of 100L without buffer.
4. What would be the main purpose of the auto by pass valves be – if I’ve understood correctly these will bypass to an alternative flow path after a critical pressure is reached? Are these at all aimed at softening any of the transients in the system when valves are opening and closing, or have I missed the mark? Whilst on the subject of transients, if my memory serves me correctly, did we say to avoid NO valves as these create quite a large water hammer?

 

Sorry again for my terrible schematic. For reference the buffer and lower ground level manifold will both be located under the stairs (within a meter of one another), whilst the upper level UFH manifold will be an approx. 2-3metre run up the wall and into the living room above. If I can help it, I'd also like to avoid having to incorporate a smart home automation system to control it all as I am trying my best to keep it as simple / straightforward as possible!

 

 

 

[PeterW]

@JulianB you need an expansion vessel on your heat pump circuit somewhere with a PRV.