ASHP/UVC/UFH Configuration

[PeterW]

Only need the 3 way or the zone valves not both

 

Bypass is in the wrong place - needs to be behind the pump

 

Can’t see your cold supply / control set - that’s how you get balanced hot and cold and the PRV for the UVC

 

Buffer with a coil is debatable - for the cost of the coil, may as well just stick more antifreeze in the system. 
 

And yes, filter before the pump / ASHP

 

And yes, PRV on the ASHP circuit but I would only run it at 1 bar so get a low pressure one. 
 

 

[LA3222]

Thanks for taking a look Peter, appears that I'm more or less along the right lines now.

 

19 minutes ago, PeterW said:

Only need the 3 way or the zone valves not both

I was trying to work out what the crack there was!

 

20 minutes ago, PeterW said:

Bypass is in the wrong place - needs to be behind the pump

Makes sense now you say it. 

 

21 minutes ago, PeterW said:

Can’t see your cold supply / control set - that’s how you get balanced hot and cold and the PRV for the UVC

I am splitting this process into four parts:

 

1. ASHP to UVC & Buffer

2. Cold mains to UVC

3. Balanced hot & cold to manifolds

4. UFH to the buffer

 

Once I have each part sorted I will merge the drawings into a master schematic.

 

23 minutes ago, PeterW said:

Buffer with a coil is debatable - for the cost of the coil, may as well just stick more antifreeze in the system. 

I have two UFH manifolds, my plan was to tap into the buffer for them. If i didn't use an indirect buffer then I would have to use an anti-freeze solution for the ground/first floor UFH circuits? I figured separating them hydraulically would keep things simpler/cheaper?

 

I think the first part of my plumbing setup is pretty much there, thanks for the help.?

[Pete]

44 minutes ago, PeterW said:

Only need the 3 way or the zone valves not both

 

Bypass is in the wrong place - needs to be behind the pump

 

Can’t see your cold supply / control set - that’s how you get balanced hot and cold and the PRV for the UVC

 

Buffer with a coil is debatable - for the cost of the coil, may as well just stick more antifreeze in the system. 
 

And yes, filter before the pump / ASHP

 

And yes, PRV on the ASHP circuit but I would only run it at 1 bar so get a low pressure one. 
 

 

 

Does the heat pump not have a built in by-pass?

 

[PeterW]

A lot of them don’t and they have a nasty habit of throwing over pressure errors and to be honest an automatic bypass and a pair of tees is change of £10 so why not just fit one and it’s done. 
 

 

[PeterW]

33 minutes ago, LA3222 said:

have two UFH manifolds, my plan was to tap into the buffer for them. If i didn't use an indirect buffer then I would have to use an anti-freeze solution for the ground/first floor UFH circuits? I figured separating them hydraulically would keep things simpler/cheaper?

So you would normally do it the other way round - the buffer is direct and the UFH circuits would have coils. Each circuit would need a fill loop and expansion vessel, so that’s now a buffer with 2 coils and 2 expansion vessels - that’s more than the £60-70 of antifreeze and bringing in a lot of complexity for what could be very simple. 

[LA3222]

9 hours ago, PeterW said:

So you would normally do it the other way round - the buffer is direct and the UFH circuits would have coils. Each circuit would need a fill loop and expansion vessel, so that’s now a buffer with 2 coils and 2 expansion vessels - that’s more than the £60-70 of antifreeze and bringing in a lot of complexity for what could be very simple. 

One coil in the tank and a low loss header linking that to two UFH circuits?

 

I think I've read so many posts now about not connecting UFH direct to ASHP that I seem to have developed an aversion to the idea!

[Pete]

11 minutes ago, LA3222 said:

One coil in the tank and a low loss header linking that to two UFH circuits?

 

I think I've read so many posts now about not connecting UFH direct to ASHP that I seem to have developed an aversion to the idea!

Think yourself lucky you have time to change it. I am mid fix and keep reading this thread and finding out we have missed stuff like auto bypass (thanks @PeterW) so off to merchants now. May find out later the pump has one but get one just in case!

[LA3222]

41 minutes ago, Pete said:

Think yourself lucky you have time to change it. I am mid fix and keep reading this thread and finding out we have missed stuff like auto bypass (thanks @PeterW) so off to merchants now. May find out later the pump has one but get one just in case!

Are you doing this yourself or do you have a plumber involved?

 

What ASHP/tank have you gone for?

[Pete]

14 hours ago, LA3222 said:

Are you doing this yourself or do you have a plumber involved?

 

What ASHP/tank have you gone for?

Hot my mate who has fitted one ASHP before and is on a steep learning curve. I went for the  9kw Panasonic Aquarea and tank with buffer although I think I could have done without it

[PeterW]

15 hours ago, LA3222 said:

One coil in the tank and a low loss header linking that to two UFH circuits?

 

I think I've read so many posts now about not connecting UFH direct to ASHP that I seem to have developed an aversion to the idea!

But to do that you need another pump as the LLH would be doing nothing ... So it’s now a buffer with coil, pump and a LLH... that’s added another £300... 

 

Think you are getting mixed up with the ASHP >> Manifold that relies on the ASHP setting the flow temperature and the flow rates, and the introduction of a buffer that allows the ASHP to heat a decent store of water and the flow is ASHP >> Buffer >> Manifold and the Manifold can pull as much or little hot water as it wants or needs. 
 

Simplify this and take the coil out ... ASHP into one side of a 100 litre buffer,  two manifolds, two blenders and two UFH circulation pumps hooked up to the other side of the buffer, tank stat on the buffer controlling the on / off of the ASHP.. job done !

[LA3222]

23 minutes ago, Pete said:

Hot my mate who has fitted one ASHP before and is on a steep learning curve. I went for the  9kw Panasonic Aquarea and tank with buffer although I think I could have done without it

How are you getting on with the task? Some pics of your install would be good if you don't mind.

 

What size UVC did you go for? I'd like a pre plumbed cylinder for ease, I know on balance it will cost a bit more than buying individual components but it will simplify a self install slightly. However, when I look at 8.5kw ecodans the pre plumbed cylinder packages are for 210l max - I want a 300l (havent actually discussed this with a rep so it may be stable!).

[LA3222]

2 minutes ago, PeterW said:

But to do that you need another pump as the LLH would be doing nothing ... So it’s now a buffer with coil, pump and a LLH... that’s added another £300... 

 

Think you are getting mixed up with the ASHP >> Manifold that relies on the ASHP setting the flow temperature and the flow rates, and the introduction of a buffer that allows the ASHP to heat a decent store of water and the flow is ASHP >> Buffer >> Manifold and the Manifold can pull as much or little hot water as it wants or needs. 
 

Simplify this and take the coil out ... ASHP into one side of a 100 litre buffer,  two manifolds, two blenders and two UFH circulation pumps hooked up to the other side of the buffer, tank stat on the buffer controlling the on / off of the ASHP.. job done !

Cheers Pete, I understand the ASHP --> UFH issue being a cycling issue due to the small volume of water within the UFH pipes. So I can see how sticking a large volume of water in between the two removes the issue. I think I just needed to work through/understand the ramifications of other options. I will plough forward now as you suggested, thanks for the advice, much appreciated.

[SuperJohnG]

 @LA3222 I think I was the same as you and was under the impression that it was better to have an indirect buffer (sure that was covered in another thread!).  

 

Same as you I was thinking ecodan pre plumbed, but I'll spend a little time pricing and understanding the system a bit better with pre plumbed vs built system. 

 

But regardless of ease. I think the hard work has been done here, a little bit more development on a final design and it'll be there and then you can cost a built system and also get the value add for selecting a cylinder which suits like a 400l if required. 

 

Nearly there! 

[LA3222]

Right folks, in particular @PeterW if you would be so kind to cast a critical eye here - this is the next piece of the plumbing puzzle.

 

It covers:

 

Mains incomer --> UVC and other Outputs

 

A few things I am pondering:

 

Are Y strainers required anywhere?

Pressure gauges anywhere - any harm in putting them in anyway?

Additional isolation valves required? Worth having more to isolate individual parts for maintenance etc?

Expansion vessels -missing? In wrong place?

 

Any feedback is much appreciated?

 

 

[PeterW]

Don’t need the first PRV and strainer - balanced cold comes off the control group that you get with the UVC. 
 

best place for UVC cold feed drain is as it goes into the tank. 
 

Hot return goes into the tank at the top, not in to the cold feed. 
 

I feed WCs off the same branch as the outside taps but that is preference - they don’t need to have soft water or be reduced pressure.  

 

[LA3222]

I've drawn the layout as if I have a naked cylinder and I'm plumbing in everything required.

 

With that in mind is the 3.5bar PRV drawn in the right place? I believe there needs to be one so that the pressure into the cylinder does  ot exceed 3.5bar and the balanced cold needs to come after it?

 

I've drawn the UVC cold drain as second to last, physically it would be right before the cold inlet on the UVC.

 

The HRC, not sure now why I drew it like that as I'm sure I read summat about it bot going in at the bottom as it disturbs the stratification etc in the UVC? - I understand which tapping you refer to.

 

Unsoftened water - I've been scratching my head over this one as there are conflicting POVs throughout the threads on the forum. Kitchen tap is the main one as I want a quooker tap so more reading needed here! 

[PeterW]

The control group comes with 4 ports. Inlet, reduced pressure outlet to the cylinder, balanced cold to the rest of the system and pressure relief, all in a single block. 
 

The Expansion vessel goes after the control group and before the cylinder, and nothing can go between them (no valves). 
 

 

[LA3222]

Thanks for the steer, you've got me looking at 'control groups' now. So aiui some of the components I have drawn individually are actually all part of one part. I will redo my drawing to show this.

 

What manufacturer/supplier would you recommend for parts to go with the UVC like the control group. A quick Google shows im looking for something like this?:

 

 

[LA3222]

Latest iteration or the plumbing from mains incomer to UVC.

 

Small changes each time but trying to flesh it out so all parts are on it which can then lead to an easy to work out materials list.

 

Any feedback is appreciated.

[LA3222]

Thought it had been much longer but seems to only have been a couple of weeks since I was last chipping away at this. I have now got Visio and have cannibalised the drawing done by Andy (cheers?) on here and now have a plumbing schematic for critique:

 

@PeterW, @Nickfromwales if you chaps could spare a few minutes to take a look and shred my plan it would be much appreciated.

 

Ta all.

 

[LA3222]

No feedback ?

 

I known its a bit of an epic read to scrutinise, I can only assume that my efforts have been exemplary and the system design is optimal??

[ProDave]

36 minutes ago, LA3222 said:

No feedback ?

 

I known its a bit of an epic read to scrutinise, I can only assume that my efforts have been exemplary and the system design is optimal??

Does the ASHP have a pump built in?  I have my suplimentary pump on the flow from the ASHP not the return (anyone else care to comment on that)

 

I personally dislike 3 port valves.  I have a 2 port valve for DHW and another two one for upstairs and downstairs UFH.  I put the 2 port valves local to the UFH or DHW tank and put the automatic bypass at the DHW tank so it was as far away from the ASHP as possible.  Many ASHP's will turn on and circulate water on their own when "off" as an anti freeze measure so need somewhere to get warm water from.

 

 

[epsilonGreedy]

3 hours ago, LA3222 said:

No feedback ?

 

I known its a bit of an epic read to scrutinise, I can only assume that my efforts have been exemplary and the system design is optimal??

 

What is your mains water pressure?

 

It looks like you have decided drinking water can be delivered via the softener?

 

Worth mentioning that clicking on the diagram pops open a higher resolution version with legible labels.

[SuperJohnG]

Only thing I woukd query is the need for a pump feeding the ASHP. What's the need for this? As it should have a pump in it? Also do you need that other expansion vessel above that pump? As no matter what you are connected to an expansion vessel at the buffer or UVC at all times. 

 

Edit: I'm only comparing this with hydraulics systems I design. I'm not stating having a pump is an issue. Id just like to know what it's for (apart from the obvious). 

Edited February 4, 2021 by SuperJohnG

[LA3222]

@SuperJohnG & @ProDaveThe pump was directed by @PeterW on the first page - an earlier iteration of the design.  The expansion vessel was added based on the drawing I found in some Ecodan documentation, this also shows a pump on the return flow too?

 

 

Dave, your point ref three port valves I'll have to think about. I need to draw the setup you described first so I can weigh it up properly.

 

@epsilonGreedy Jonathon, mains pressure is just under 3bar. I do intend to use a water softener, not decided yet on whether to take a hard water supply for drinking water. Its something that has been discussed elsewhere here, some do, some don't. I think I'd have to try it to see how we get on with it maybe before making a decision.