Numpty plumbing questions

[Nick1c]

Our first fix plumbing will start in a week or so and there are a few things I can think of (& lots I have yet to think of!) that I haven’t got my head around. 
We plan to use a Sunamp, heated via a Vaillant ASHP & Pv which will supply a kitchen and 3 bathrooms ( each will have shower, basin, toilet, one will have a bath as well). The kitchen and bathroom with the bath will be within 5m of the Sunamp, the other 2 bathrooms will be 17-20m away. One of these is our en-suite. The supply into the hose is 28mm from the meter, but only 15mm from the mains to the meter (a 5m or so run). The water company tested the pressure & flow, they got 40l/min at 3 bar. 
 

Manifolds - I can see the benefits for the hot supply, other than ease of isolation is there any benefit on the cold side?
Pipe diameter - 10mm to hand basins/toilets, 15mm (?22) to kitchen tap/showers/bath?

Pipe insulation - yes or no? Presumably a definite yes if using a HRC. 

HRC - how does this work on a thermal store/ Sunamp? These seem to effectively work as instantaneous heaters. 

Accumulator - are we likely to need one, if so are they a good idea or is it better/more cost effective to pay to have 28mm put in from the main?

 

I have no doubt more questions will come......

 

[joth]

14 hours ago, Nick1c said:

We plan to use a Sunamp, heated via a Vaillant ASHP

High temperature ASHP presumably? I didn't think existing Vaillant models work hot enough to charge a Sunamp

 

Do you already have the Sunamp ordered? I heard they have quite long lead time but interested if that's not the case. 

Edited January 28, 2020 by joth

[Nick1c]

@joth yes, one of the higher temp ones, I believe they will be available by May when I hope to be needing one. My installer hasn’t mentioned any problems getting hold of a Sunamp, but again it won’t be needed till May. 

[Nickfromwales]

19 hours ago, Nick1c said:

Manifolds - I can see the benefits for the hot supply, other than ease of isolation is there any benefit on the cold side?
Pipe diameter - 10mm to hand basins/toilets, 15mm (?22) to kitchen tap/showers/bath?

Pipe insulation - yes or no? Presumably a definite yes if using a HRC. 

HRC - how does this work on a thermal store/ Sunamp? These seem to effectively work as instantaneous heaters. 

Accumulator - are we likely to need one, if so are they a good idea or is it better/more cost effective to pay to have 28mm put in from the main?

 

I have no doubt more questions will come......

With mixer outlets you need to isolate both to successfully shut them off. Remember you cant use manifold valves to attenuate flow rates, it's on or off.

Pipe diameter is 15mm max. Do NOT use 22mm for anything other than hot and cold to the SA or heating circs. This assumes you dont want to do satellite manifolds, just keeping everything in the plant room.

Insulate the HRC elements, otherwise just the hot and cold before the manifolds etc and heating circs.

Simple, just use a pair of NRV's to allow the return flow back into the SA cold inlet. One ( single check not double check ) valve goes between the HRC pump and the SA, and one goes into the cold feed to the SA just prior to where the HRC and the cold feed tee together. I think for your instance just small bore hot feeds to the nearest basins / sinks only, and HRC to the basins at the furthest location only. Dont have the HRC doing the baths or showers, thats a waste of time and heat energy.

 

Still unsure why anyone in a PH would go to the trouble of fitting a HT ASHP to heat a SA for just DHW TBH  unless it was a huge dwelling and RHI was worth chasing.....KISS says fit a size 12 SA and heat it once a day on Octopus / similar for DHW at < grid gas costs, + zero maintenance / service by comparison. Cheap monoblock for UFH and job done.

[Nick1c]

Thanks. 
10/15mm everywhere it is. Uninsulated makes life easier & cheaper ?
I am tempted to skip the HRC to the far bathrooms as I/we don’t mind washing hands in cold water, which would be the main benefit.  

Still not sure of the benefit of a cold manifold, why not use a ‘traditional’ circuit & isolation valves?

Any thoughts on an accumulator vs upgrading the supply?

I don’t understand why the maintenance costs would be different with a different ASHP, I was under the impression that they are by in large effectively one or more ‘black boxes’ which need replacing if anything goes wrong & maintenance comes down to keeping the filters clean. 

[Nickfromwales]

11 hours ago, Nick1c said:

Thanks. 
10/15mm everywhere it is. Uninsulated makes life easier & cheaper ?
I am tempted to skip the HRC to the far bathrooms as I/we don’t mind washing hands in cold water, which would be the main benefit.  

Still not sure of the benefit of a cold manifold, why not use a ‘traditional’ circuit & isolation valves?

Any thoughts on an accumulator vs upgrading the supply?

I don’t understand why the maintenance costs would be different with a different ASHP, I was under the impression that they are by in large effectively one or more ‘black boxes’ which need replacing if anything goes wrong & maintenance comes down to keeping the filters clean. 

How much is the split HT ASHP going to cost ?
Let’s  assume its over £2.5k.... Anything over that is money down the drain in a PH afaic now these cheap EV directed electricity tariffs exist.

No sale, sorry  

[Dan F]

On 28/01/2020 at 06:45, Nickfromwales said:

Remember you cant use manifold valves to attenuate flow rates, it's on or off.

 

Are there any options available that do allow satellite manifolds to adjust flow rates? 

[Nickfromwales]

23 hours ago, Dan F said:

 

Are there any options available that do allow satellite manifolds to adjust flow rates? 

Not accurately, and they’re all quite noisy when they get used like that. Just use flow restrictors at the individual outlet and keep the isolators for.........isolating  

[Dan F]

10 minutes ago, Nickfromwales said:

Not accurately, and they’re all quite noisy when they get used like that. Just use flow restrictors at the individual outlet and keep the isolators for.........isolating  

 

Yeah, but want them accessible should I need to "maintain" them in the future, which is why I want them to be either part of manifold or next to manifold and not behind tiling in bathroom.  Any options that would allow this?

 

Edited December 18, 2020 by Dan F

[PeterW]

5 minutes ago, Dan F said:

 

Yeah, but want them accessible should I need to "maintain" them in the future, which is why I want them to be either part of manifold or next to manifold and not behind tiling in bathroom.  Any options that would allow this?

 

Flow restrictors are fitted to the outlet of the tap itself so they are always accessible. There should be nothing buried in walls. 

[Dan F]

4 minutes ago, PeterW said:

Flow restrictors are fitted to the outlet of the tap itself so they are always accessible. There should be nothing buried in walls. 

 

What I want to do is to comply with Part G water usage regulations without necesarily having to buy from a limited range of showers that have flow restrictors incorporated.  The thought that a plumber could instead restrict the flow at (or close to) a satalite manifold instead.

Edited December 18, 2020 by Dan F

[PeterW]

Ok so I have no idea the last time someone checked a flow for Part G... and I just fit tap restrictors and the same with showers at the heads. Someone comes along and removes them a week later, what do I do..?  ??‍♂️

[Dan F]

11 minutes ago, PeterW said:

Ok so I have no idea the last time someone checked a flow for Part G... and I just fit tap restrictors and the same with showers at the heads. Someone comes along and removes them a week later, what do I do..?  ??‍♂️

 

Taps are all 5.7l/min which should be fine.  Just need a way to restrict showers, but not sure how restricting at the head would work if installing these:  https://www.amazon.co.uk/dp/B075QMDFB8

 

I might need to put a restrictor inline from manifold to shower to comply, but ensure they are accesible should I ever need to remove them (for maintainence of course)...

 

 

Edited December 18, 2020 by Dan F

[Nickfromwales]

1 minute ago, Dan F said:

 

Taps are all 5.7l/min which should be fine.  Just need a way to restrict a showers and not sure restricting at the head will work if installing one of these:  https://www.amazon.co.uk/dp/B075QMDFB8

 

I might need to put a restrictor inline from manifold to shower to comply, but ensure they are accesible should I ever need to remove them (for maintainence of course)...

 

 

You are worrying about a problem that won’t exist. Chill out   

An in-line restrictor fitted in the shower head and handset in minutes will sort this instantly. Available in different Lpm ‘sizes’ to suit each outlet. 

[Dan F]

Agree, part G not major issue. But the bathroom designer is insisting on specifying products that comply. This means her specifying either low flow rate showers or restrictors.

 

@Nickfromwales I get your point, but not sure how/where you would you put a accesible restrictor inline with shower head like one i linked to. This is why i was assuming restriction at (or next to) manifold. 

[PeterW]

4 minutes ago, Dan F said:

But the bathroom designer is insisting on specifying products that comply. This means her specifying either low flow rate showers or restrictors.

Sorry who is paying her bill..?? 

 

If any specifier or designer started to tell me as a client that I had to do something (which you don’t ...) and won’t follow client instruction then I would be off like a shot.
 

All of the Twyford taps for example come with screw in aerators that can be changed for different coloured low flow ones - quick and simple and designed for varying usages. 
 

Sounds like your designer has a very insular view of what is acceptable. 
 

 

[Dan F]

Well, to be fair, it's her document (or part G spreadsheet) that has to go to building control, that's the only reason she wants it to comply. What we install is a different matter and i doubt anyone will ever check.

 

Taps are non-issue, it's the showers where head restrictors dont seem to feasible, but we're telling her we don't want to install the "ecojoy" 9l/min variant.

[Russell griffiths]

4 hours ago, Dan F said:

Agree, part G not major issue. But the bathroom designer is insisting on specifying products that comply. This means her specifying either low flow rate showers or restrictors.

 

@Nickfromwales I get your point, but not sure how/where you would you put a accesible restrictor inline with shower head like one i linked to. This is why i was assuming restriction at (or next to) manifold. 

Tell the designer it’s your house, pick the stuff you want. Simple. 

[Russell griffiths]

3 hours ago, Dan F said:

Well, to be fair, it's her document (or part G spreadsheet) that has to go to building control, that's the only reason she wants it to comply. What we install is a different matter and i doubt anyone will ever check.

 

Taps are non-issue, it's the showers where head restrictors dont seem to feasible, but we're telling her we don't want to install the "ecojoy" 9l/min variant.

I’ve not sent any document to building control regarding this, you just state that you will comply. 

 

When we lived in oz this is a major part of building control, they come along and measure the flows, you pass, then you pull the restrictions out. 

Building a house is hard, don’t make it harder than it needs to be, just tell them what they want to here.