Use BUS or self-install?

[Beelbeebub]

10 minutes ago, JohnMo said:

Two resistors, 10p each and a relay in a box £5 to £10. No programming or anything special. Plus you need to output a resistance not input it. Taking an on off call for heat from the eDual and output a resistance to fool the ASHP into starting DHW heating.

I thought it was the edual that required the resistance?

 

A number of HPs can take an on/off input to start DHW mode

[JohnMo]

21 minutes ago, Beelbeebub said:

thought it was the edual that required the resistance?

 

A number of HPs can take an on/off input to start DHW mode

Agreed, mine does, but means you cannot use the multi purpose contacts fir other things.  The OP said

On 19/12/2023 at 17:07, oranjeboom said:

dealings with Sunamp and installer is that the controller on eDuals would need to be replaced as these have  " a switching circuit which won’t be compatible with most heat pump controls as they utilise a resistance reading to generate a demand or satisfied call

So possibly his heat pump will not have on/off contacts or the installer hasn't read that far in to the installer manual.

[Beelbeebub]

1 hour ago, JohnMo said:

So possibly his heat pump will not have on/off contacts or the installer hasn't read that far in to the installer manual.

Wouldn't surprise me if it was the latter - HPs, especially the Asian ones seem to have a massive array of functionality for every conceivable circumstance.

[oranjeboom]

On 23/12/2023 at 12:29, JohnMo said:

Agreed, mine does, but means you cannot use the multi purpose contacts fir other things.  The OP said

So possibly his heat pump will not have on/off contacts or the installer hasn't read that far in to the installer manual.

 

Not chosen a heatpump...installer is keen on EcoDan, but no sufficient temp outflow for the Sunamp unit. Being limited to what Sunamp's list of compatible list of HPs (for the eDual):

 

Daikin Altherma 3HHT R32 Series

Ecoforest ecoAIR PRO series

Ecoforest ecoGEO PRO R290 Series

Phnix Greentherm R290 Series

Samsung EHS HTQ R32 Series

Trianco Activair R290

Vaillant Arotherm Plus

 

However, the external controller for the eDual won't is not compatible with the above due to it's switching circuit....

 

So either it's me finding an electrician who knows how to adjust things in the controller or convince Sunamp of shipping me a new external controller with the compatible wizardry. 

 

Installer is ignoring my calls as he's fed up with dealing with Sunamp and has easier jobs to be getting on with and Sunamp hate dealing with the general public. 

[SuperPav]

If you've not done it yet (we're in the same boat as you, holding out till the house is built enough to be able to go through BUS, while shivering with a 3kW willis and a 12kW shower), we're considering using these guys as they'll do the sign off and MCS paperwork for the BUS. I've been in touch and essentially they want £1.5k for the privilege, but if that gets you £7.5k it's still not a bad deal if you can DIY it. I've also got the advantage of being able to buy/supply the ASHP and install it via my ltd co (i'd still be doing it!) thereby getting the VAT back, which in itself is worth £1k or so..

 

https://www.unitherm.co.uk/pages/mcs-design

Edited January 12 by SuperPav

[JohnMo]

3 hours ago, SuperPav said:

holding out till the house is built enough to be able to go through BUS,

Why - there is no requirement to be fully built, on a self build.  Do yourself favour and read all the requirements. No EPC required either, because you already comply with building regs.

[JohnMo]

Or buy everything before you complete and get the vat back anyway. £1.5k to do the paperwork why bother, you can get a heat pump for that if you shop around 

[SuperPav]

Mainly because if I got a 12kW heat pump with cylinder for £6k, even with the £1.5k paperwork fee, I'd get it all covered with £7500 BUS monies. If I buy it myself, without it, it would cost me £5k net of VAT, which I cannot reclaim.

 

Re requirement to be fully built, I was under the impression having read the requirements is that the system would need to be commissioned before the grant is paid, but I don't know how you commission it when the upstairs hasn't got any rooms/rads yet? 

[joth]

1 hour ago, SuperPav said:

but I don't know how you commission it when the upstairs hasn't got any rooms/rads yet? 

Can the downstairs emitters fulfill the whole building heating demand?

If so just cap off the pipes to upstairs and commission downstairs.

Installing rads upstairs then becomes a retrofit upgrade job. Nothing in the BUS says you can't make future modifications to a system after it's installed? (Unlike the old RHI that came with 7 year strings attached)

 

[oranjeboom]

On 11/01/2024 at 21:42, oranjeboom said:

 

Not chosen a heatpump...installer is keen on EcoDan, but no sufficient temp outflow for the Sunamp unit. Being limited to what Sunamp's list of compatible list of HPs (for the eDual):

 

Daikin Altherma 3HHT R32 Series

Ecoforest ecoAIR PRO series

Ecoforest ecoGEO PRO R290 Series

Phnix Greentherm R290 Series

Samsung EHS HTQ R32 Series

Trianco Activair R290

Vaillant Arotherm Plus

 

However, the external controller for the eDual won't is not compatible with the above due to it's switching circuit....

 

So either it's me finding an electrician who knows how to adjust things in the controller or convince Sunamp of shipping me a new external controller with the compatible wizardry. 

 

Installer is ignoring my calls as he's fed up with dealing with Sunamp and has easier jobs to be getting on with and Sunamp hate dealing with the general public. 

 

Going to buy a lottery ticket tonight....I actually had someone from Sunamp call me this afternoon about my external control unit. Essentially I just need to find a HT HP that has a switching circuit (rather than a heat sensor)...the old eDual units were compatible with LG HT Therma models. 

 

I've had a brief look at the latest LG units...not seeing anything obvious that shows whether the latest offerings work via heat sensor or switching circuit. Does anyone on here know more? Or what I should be looking for in there schematics?

 

[sharpener]

53 minutes ago, oranjeboom said:

Essentially I just need to find a HT HP that has a switching circuit (rather than a heat sensor)...the old eDual units were compatible with LG HT Therma models. 

 

Of those on yr list the Vaillant Arotherm Plus can defo be controlled by third party controls with a voltage-free contact closure.

 

My Honeywell Evohome wireless TRVs' boiler output is not volt-free so I have just installed an extra relay in anticipation of my HP install for this reason.

[JohnMo]

1 hour ago, oranjeboom said:

Essentially I just need to find a HT HP

Or just heat the SA on E7 or similar tariff.

[oranjeboom]

16 hours ago, JohnMo said:

Or just heat the SA on E7 or similar tariff.

 

Yeah, but for the BUS grant I need the ASHP to be doing the charging/heating of the Sunamp unit...

 

Although I will need to apply to Ofgem first to see whether they will approve this setup for the grant. According to my installer...

 

Anyone on here been accepted for the grant with Sunamp in the mix??

 

 

17 hours ago, sharpener said:

 

Of those on yr list the Vaillant Arotherm Plus can defo be controlled by third party controls with a voltage-free contact closure.

 

My Honeywell Evohome wireless TRVs' boiler output is not volt-free so I have just installed an extra relay in anticipation of my HP install for this reason.

 

Okaaaay....   Can you give me any examples? I'm fairly clueless here. I'm having to make suggestions to installer and keep getting drip-fed by Sunamp to make this whole thing work. It really should be a simpler affair!

[sharpener]

38 minutes ago, oranjeboom said:

Can you give me any examples?

 

Here is the connection diagram for the Vaillant VR71 interface box. You can see that terminals S6, S7 and S8 are used for the heat demands for up to 3 different zones.

 

Note 3 says they are contacts closed to stop heating, this is the reverse of the usual convention but it can anyway be changed to "closed for heat" in the installer menu.

 

In my case the zones will be rads, UFH and a thermal store. Vaillant have signed off the schematics with

• the Honeywell external controls connected to S6,
• the existing UFH manifold controls to S7 and
• a timeswitch to S8

so I am 100% confident they are happy with external third party controls, and a simple contact closure from your Sunamp (of either sense) should work fine.

 

I do not know whether the Sunamp should be treated as a separate zone or as a substitute for the usual HW cylinder. Your installers should agree a set of schematic diagrams with Vaillant for your Sunamp application, they will not support it unless the design is signed off like that. If you can get them to give you a copy and post it here we can tell you more.

 

Edited January 20 by sharpener

[sharpener]

11 hours ago, oranjeboom said:

Yeah, but for the BUS grant I need the ASHP to be doing the charging/heating of the Sunamp unit...

 

Although I will need to apply to Ofgem first to see whether they will approve this setup for the grant. According to my installer...

 

Provided the HP is the ultimate source of all the heat for the DHW I would think it complies with the MCS rules.  Your installer will have to send OFGEM a copy of your quotation to apply for the BUS voucher, beyond that I don't think they would be concerned if it is stored in a Sunamp (and I don't know of a mechanism for getting their approval). Also ask him where it requires details of the Sunamp on the MCS paperwork he has to file after completion.

You might find a current thread on this forum interesting as there is a Neil Gascoigne there looking for advice on setting up his newly installed Sunamp DHW installation.

[oranjeboom]

On 20/01/2024 at 12:35, sharpener said:

Here is the connection diagram for the Vaillant VR71 interface box

 

I've spent a while trying to find this online, as I'm hoping to send this to my installer to see what he thinks. Is this online also? I tried looking under Vaillant also....but no....

 

Thank you!

[sharpener]

43 minutes ago, oranjeboom said:

Is this online also?

 

https://www.manualslib.com/manual/1583441/Vaillant-Multimatic-700-2.html?page=94#manual

 

Also I see Neil Gascoigne reports his Sunamp has an internal temp sensor which takes the place of the Vaillant VR10 DHW sensor and is wired to the corresponding terminals in place of it. I think these are SP1 on the Heat Pump Interface unit (not the VR71 itself).

 

Edited January 22 by sharpener

[ReedRichards]

Isn't the phase change temperature of a standard Sunamp a bit too high for an ASHP?  It certainly used to be; perhaps a newer ASHP capable of a higher temperature output would be okay?    

[sharpener]

1 hour ago, ReedRichards said:

Isn't the phase change temperature of a standard Sunamp a bit too high for an ASHP?  It certainly used to be; perhaps a newer ASHP capable of a higher temperature output would be okay?    

 

IIRC from the FB link upthread it would appear to need flow = 70C. Sunamp have several variants tuned to different HPs inc the LT Daikins.

[ReedRichards]

3 hours ago, sharpener said:

Sunamp have several variants tuned to different HPs inc the LT Daikins.

 

But isn't @oranjeboom wanting a heat pump to work with a Sunamp they already own?  If so, it's unlikely to be a "special".  

[oranjeboom]

7 hours ago, ReedRichards said:

 

But isn't @oranjeboom wanting a heat pump to work with a Sunamp they already own?  If so, it's unlikely to be a "special".  

Yes, I have an earlier model, the "eDual", external controller which is the issue as it does not rely on a heat sensor.

 

12 hours ago, ReedRichards said:

Isn't the phase change temperature of a standard Sunamp a bit too high for an ASHP?  It certainly used to be; perhaps a newer ASHP capable of a higher temperature output would be okay?    

 

65 degrees I believe

[ReedRichards]

I looked up previously that the phase change temperature of the usual material in a Sunamp box is 58 C.  So to get it to change phase in a reasonable amount of time you need water hotter than that, maybe

1 hour ago, oranjeboom said:

65 degrees I believe

 

I think some of the very latest heat pumps can manage 65 degrees, mine won't without the help of an immersion heater and that's inside my hot water cylinder so wouldn't work for this application..  The thing to look at in the spec. is what COP you should aspire to for a 65 C output (and some averaged outside temperature).

[sharpener]

58 deg phase change is pretty consistent with the requirement elsethread that the Vaillant supply 70C flow. As you point out the CoP won't be brilliant. Maybe with only 1.5 people it won't matter on E7. If you can accept a longer charging time then maybe 65 would be better?

 

Problem seems to be in the control of it. The Vaillant won't care if its DHW sensor doesn't get a proper reading, if it sees "cold" it will just keep trying for as long as the DHW is programmed for (IIRC the default is 45 mins followed by 45 mins lockout). The more important thing is the call for heat and it appears the eDual controller can provide that as a contact closure which the Vaillant HP will accept.

 

Is your installer happy with this now @oranjeboom?

 

Even if it can't, I don't see any problem with the physics of the thing running entirely open loop, once the material has transitioned to liquid at 58C it will rise slowly to 70C and after that it will not absorb any more heat. So the HP will shut itself down once unable to maintain 5K dT.

[oranjeboom]

On 20/01/2024 at 12:35, sharpener said:

I do not know whether the Sunamp should be treated as a separate zone or as a substitute for the usual HW cylinder. Your installers should agree a set of schematic diagrams with Vaillant for your Sunamp application, they will not support it unless the design is signed off like that. If you can get them to give you a copy and post it here we can tell you more.

 

So this is what the installer has come up with in tandem with Vaillant (see PDF). Still awaiting for Sunamp to review and approve that. Sunamp also came back with this suggested fix for the external Sunamp control unit (which I have questioned whether this is their 'final' solution as the wording seems a bit haphazard!):

 

Vailant and sunamp schematic (1).pdf

[sharpener]

So yes, Vaillant's schematic is treating the SA just like a hw tank.

 

SP1 is the input for their usual VR10 thermistor sensor on/in the tank. AFAIK it's not an input that can accept a demand signal from voltage-free contacts. Maybe they just are using it to short out the sensor inputs, this would simulate a high temp signal and so turn the DHW off?

 

 

 

Don't understand the connections shown to terms 3 & 4 on the SA as the inline pic shows 3 is the earth of flex B and 4 is the live of flex C. Live applied to SP1 will probably blow it up so they are presumbably referring to a different set of terms somewhere else.

 

If you need to control the HP's DHW output from contact closures there are two ways I can think of.

 

1. This morning I had a conversation with one of Vaillant's systems people and he said a contact across terms ME will force DHW on until it is satisfied and after that force the heating on so long as it continues. This is intended for getting the HP to run whenever there is surplus PV or off-peak electricity available regardless of the schedules. You would have to think carefully about the timings for this.

 

2. You could fit an VR71 expansion box and configure a second zone as a DHW zone and then use contacts across S7 to control it. Try the installation menu in the simulator here, you will see if you do this then the available settings become those for a DHW circuit not a heating circuit.

 

Sorry I don't know enough about SA connections so the reference to purple/white resistor wiring passes over my head. What are they trying to achieve with it? What does Rly 2 normally do and why do they want to reverse the sense of it?

 

What needs controlling about the SA anyway, the HP will supply heat when its DHW schedule demands it and it will stop when SP1 says it is hot enough.