Three way diverter valve

[mk1_man]

Again something that has probably been discussed so apologies.   I have gone to a lot of effort to make sure I have primaries in 28mm, swept bends, minimal restriction etc but now I have come to sourcing the 3 way diverter and the traditional Honeywell type appears very restrictive.  Just wondering what peoples thoughts were and what others had installed.  I am biased towards the ESBE VRG131 at the moment, probably in the 1 1/2" size.

[JohnMo]

I really wouldn't worry the restriction is for a very short length. I heat my cylinder via 22mm primary to a 28mm Honeywell diverter with no issues from a 6kW ASHP. Your cylinder may come with a diverter - mine did, so worth a check

[Originaltwist]

The thing with diverter valves is that flow stops dead during the changeover - can't imagine heat pumps like that.  Coster used to do one with constant flow but any other suggestions?

[ProDave]

Don't use a diverter.  Use 2 (or more) 2 port valves.

[JohnMo]

49 minutes ago, Originaltwist said:

The thing with diverter valves is that flow stops dead during the changeover - can't imagine heat pumps like that.  Coster used to do one with constant flow but any other suggestions?

Not sure it can, there is a swinging flap that closes one port - the other port open, as the flap is driven to close a port the other port opens, most the transition two ports are open.

 

Done two interlinked 2 ports would stop flow.

 

Nothing wrong with a 3 port valve, they use the same actuator as as 2 port, so all the midpoint reliability issues are not present.

[JoeBano]

I’ve got 2x2 port valves with a relay to shut the heating while the hot water demand is there. Bypass to protect the pump. I only did this setup because I already had the kit no point throwing good stuff out 

[sharpener]

9 minutes ago, JoeBano said:

I’ve got 2x2 port valves with a relay to shut the heating while the hot water demand is there. Bypass to protect the pump. I only did this setup because I already had the kit no point throwing good stuff out 

 

This is a Vaillant approved method, I have their official schematics that show it.

 

Tell us @mk1_man what controls you intend to fit, you may not even need the relay.

 

How much of the install are you doing yrself, sounds like quite a lot?

 

BTW a 7kW HP hardly needs 28mm pipe anywhere in the system unless the runs are extremely long.

[mk1_man]

Hi, planning on using Vaillant control, not sure what combination I need.  I would like to have two wireless controllers / thermostats as part of the setup, zone 1 - whole ground floor, then one on top floor as separate zone.   Plan is run open loop for whole ground floor with no buffer etc, approx 150m2  and then run single zone on 1st floor but with room stats which I have on old system to limit each bedroom temp in case they get to hot.

 

[sharpener]

Sounds like you need these Vaillant schematics pp 84-86.pdf, which is an abstract from their big online book.

 

If the zone valves for rads and UFH are wired as shown to the VR71 they are automatically de-energised when DHW is operating so you don't need a 3-port diverter at all, just a 2-port wired to UV1.

 

If there is a consolidated voltage-free call for heat from the rad stats that goes to S6 on the VR71.

 

I still don't quite understand what stage you have got to, you mention an installer but appear to be doing the system design and choosing parts as you go along. What am I missing?

[mk1_man]

I am doing install myself under the umbrella of MCS.  Waiting on schematics but in the meantime looking at all options that may optimise the system and hopefully input from others. Things that work well and not so well etc.  Cheers

 

 

[sharpener]

 

12 minutes ago, mk1_man said:

I am doing install myself under the umbrella of MCS. 

 

Brilliant, best of luck with it. Have you discovered this simulator?

 

Now that it seems my Vaillant installer has turned into a pumpkin I would be grateful to know who yr MCS umbrella firm is, I haven't been able to find one that does Vaillant myself.

 

Feel free to PM me with any info or queries if you don't want to post them here.

 

[mk1_man]

What part of country are you at?

[sharpener]

South Hams, Devon.

 

Meantime I have seen yr other threads about Alto, but when I contacted them they did not do Vaillant and would not do custom designs.

 

So if you have migrated from an 11kW Ecodan to a 7kW Vaillant I am guessing you have gone with someone else?

[JohnMo]

1 hour ago, sharpener said:

Vaillant

What's so special about them except the huge price?

[sharpener]

I started on this with a quite open mind and of the three installers I got quotes from the front-runner originally proposed a Stiebel Eltron. They too are expensive and the 15kW is an extremely bulky single-fan model which would have taken up a lot of our kitchen yard. They then suggested a 12kW Vaillant which is taller, thinner and can go closer to the wall of the house. So I said yes to that. It has almost as much output but still needed a bit of playing with the MCS calcs.

 

Since then I have put in a lot of time and effort working to get a manufacturer-approved system design which solves a number of technical issues, and ideally I don't want to have to start again with a different brand. Also it would mean re-applying for PP and DNO approval.

 

Mitsubishi would probably be next on my list but a whole new learning experience to get to the same point. As reported here I liked the look of the Grant R290 models on show at the exhibition but they don't seem to be available yet. At the more cheap and cheerful end CoolEnergy look interesting but the form factor is against them. Octopus say I am out of area, Good Energy have quoted for 2 x 12  kW Midea(!) which I do not have room for.

 

 

[HughF]

On 13/04/2024 at 12:08, sharpener said:

 

This is a Vaillant approved method, I have their official schematics that show it.

 

Tell us @mk1_man what controls you intend to fit, you may not even need the relay.

 

How much of the install are you doing yrself, sounds like quite a lot?

 

BTW a 7kW HP hardly needs 28mm pipe anywhere in the system unless the runs are extremely long.

My vaillant pre-plumbed cylinder came with a Honeywell 3 port…. Go figure…

[HughF]

On 13/04/2024 at 15:18, JohnMo said:

What's so special about them except the huge price?

Best controls (room stat will auto-adapt your weather comp curve for you, yes I know Mitsubishi also has auto adapt). Best backup if you’re an installer (vaillant take care of it all)

[JohnMo]

1 minute ago, HughF said:

room stat will auto-adapt your weather comp curve for you

My Atag boiler did that also, unless you have UFH then it just screws the system up because the dalay caused by the floor heating up, same as Mitsubishi heat pumps do - they say not to use with UFH.

[HughF]

Just now, JohnMo said:

My Atag boiler did that also, unless you have UFH then it just screws the system up because the dalay caused by the floor heating up, same as Mitsubishi heat pumps do - they say not to use with UFH.

Yep, I figured most people will be running with radiators, hence my statement…

[sharpener]

41 minutes ago, HughF said:

My vaillant pre-plumbed cylinder came with a Honeywell 3 port…. Go figure…

 

For a new system it's entirely reasonable. For retrofit less so but then if you have been told you need a new cyl then the odd valve is down in the noise.

 

Many ppl seem to be against pre-plumbed, they are intended to be foolproof so fools can install them, but constrain the layout as all the ch flow has to go via the cyl location whether sensible or not. Fine if there is a central plant room but not good if the cyl is going in the loft.

 

Also the Vaillant FB page has reports of poor quality control, no 100% end-of-line pressure testing and hence fittings leaking on arrival. Used to be made by OSO, maybe they have changed to a cheaper supplier? Gledhill ditto, reports of leaks and also rattling noises from inadequately supported coils. Recent Honeywell valves as well, reports of balls becoming detached.

[HughF]

39 minutes ago, sharpener said:

 

For a new system it's entirely reasonable. For retrofit less so but then if you have been told you need a new cyl then the odd valve is down in the noise.

 

Many ppl seem to be against pre-plumbed, they are intended to be foolproof so fools can install them, but constrain the layout as all the ch flow has to go via the cyl location whether sensible or not. Fine if there is a central plant room but not good if the cyl is going in the loft.

 

Also the Vaillant FB page has reports of poor quality control, no 100% end-of-line pressure testing and hence fittings leaking on arrival. Used to be made by OSO, maybe they have changed to a cheaper supplier? Gledhill ditto, reports of leaks and also rattling noises from inadequately supported coils. Recent Honeywell valves as well, reports of balls becoming detached.

The other thing to be aware, if your heat pump only had a dhw valve live (or a heating valve live) output, instead of a separate switched live for each valve, you’ll need some relay voodoo to control the 2x 2 ports.

 

luckily mine has both, but I ended up using a 3 port anyway because it was already on the cylinder.

[sharpener]

5 hours ago, HughF said:

you’ll need some relay voodoo to control the 2x 2 ports

 

Yes but since the OP wants two zones he will mostly likely be fitting a VR71 wiring centre and this has 3 separate outputs for up to 3 zones in addition to the HW.

 

So no relay needed in his case though I appreciate the advice was useful and intended more generally.

 

On 13/04/2024 at 12:18, mk1_man said:

I would like to have two wireless controllers / thermostats as part of the setup, zone 1 - whole ground floor, then one on top floor as separate zone.