BUS Grant requirements (conflicting info)

[Chanmenie]

Just now, HughF said:

Yep, that's a bargain, given the retail price (which is unreasonable)...

Yeah they are bloody expensive, not up to a Stiebel Eltron though they are really expensive.

I do also think the Veismann indoor unit is very neat compared to most separate DHW tanks and associated gubbins, it doesn’t take up much more if any space than a traditional ( non slimline ) tank 

[Rudski]

11 hours ago, HughF said:

Any install by a heat geek or other competent installer... Buffer bad...

So when I've looked for a heat Geek, it brings up an installer local to us, only one mind you then has this caveat below, doesn't really inspire confidence, have they just registered on their website for more work?

 

Heat pump installs performed by this installer are not guaranteed or monitored by Heat Geek

 

[HughF]

1 hour ago, Rudski said:

So when I've looked for a heat Geek, it brings up an installer local to us, only one mind you then has this caveat below, doesn't really inspire confidence, have they just registered on their website for more work?

 

Heat pump installs performed by this installer are not guaranteed or monitored by Heat Geek

 

To be honest, the hydronic design of these things is so piss easy, I could sketch it out on an envelope for you and you could just get a plumber to press it all up. 
 

It’s not rocket surgery this stuff.

 

 

[Rudski]

27 minutes ago, HughF said:

To be honest, the hydronic design of these things is so piss easy, I could sketch it out on an envelope for you and you could just get a plumber to press it all up. 
 

It’s not rocket surgery this stuff.

 

 

One, try getting a plumber around here! Two, it might be Piss easy but getting a plumber, see one, and try getting one that likes to go out of his comfort zone from a fag packet sketch, I understand reading on the pages of FB heat geeks etc the bad news will always be more prevalent than the good news stories, but it seems depending where you are in the country and the amount of people installing systems that do not do what they're supposed to do is significant, or maybe these people are expecting too much from these systems, OR have been promised something they haven't been given.

 

I've dropped a guy an e mail who is accredited by the Heat Geek scheme, but he's 1 1/2 hrs away from us 😟 so we'll see if interested.

[JohnMo]

32 minutes ago, HughF said:

hydronic design of these things is so piss easy

Especially with UFH. Pipe from heat pump to 3 port diverter. Each side of diverter, to either to UFH hot port or cylinder top coil tapping. Return piping from UFH cold port to heat pump, cylinder return tees into return from UFH. Strainer in return line prior to heat pump and after tee.

 

Heat geek design done. 22mm fine up to 6kW generally, unless long runs. Up 10kW 28mm on primary runs.

 

Bigger the heat pump the better the quality of 3 port diverter you need, to reduce pressure loss. The other thing to assess is system volume, for cycling.

[HughF]

21 minutes ago, Rudski said:

One, try getting a plumber around here! Two, it might be Piss easy but getting a plumber, see one, and try getting one that likes to go out of his comfort zone from a fag packet sketch, I understand reading on the pages of FB heat geeks etc the bad news will always be more prevalent than the good news stories, but it seems depending where you are in the country and the amount of people installing systems that do not do what they're supposed to do is significant, or maybe these people are expecting too much from these systems, OR have been promised something they haven't been given.

 

I've dropped a guy an e mail who is accredited by the Heat Geek scheme, but he's 1 1/2 hrs away from us 😟 so we'll see if interested.

Just get him on time + materials and tell him to crack on, you’re only paying him to sling pipe and press fittings.

[BotusBuild]

On 22/01/2025 at 21:04, Dillsue said:

Does the BUS grant even apply to new builds?? Isn't it for replacing fossil fuelled heating.

Yes, just had mine installed

[BotusBuild]

On 22/01/2025 at 12:09, Rudski said:

we hadn't planned for anything else upstairs

I did plan for UFH both floors, but do wonder what will be on when given the way our house is built.

We are getting the BUS grant, the HP is installed and working, but the UFH is not yet connected upstairs. Maybe this a way round it for you. Put the manifold into a cupboard and just isolate it 😁

[ringi]

The Viessmann "defrost buffer" is connected to the CH by a value that enables the buffer to be both disconnected from CH and the CH to be bypassed. When a defrost is pending, the heat pump 1st heat the small buffer (and nothing else) to a high temperature, then uses the hot water in the buffer to defrost the heat pump.  This results in the defrost not removing any heat from the CH system, so keeps radiators at a more stable temperature while the defrost is running.  

(This defrost buffer also contains an electric backup heater, so a defrost of the heat pump is always possible regardless of CH water temperature, CH volume, and outside temperature.)

[sharpener]

16 hours ago, ringi said:

This results in the defrost not removing any heat from the CH system, so keeps radiators at a more stable temperature while the defrost is running.  

 

Sounds plausible and explains why it only needs 16l tank.

 

But this is for defrost, and as upthread antifreeze protection is a different beast. None of this will protect the hp if there is a power cut and you are away so I do not understand how Viessman can say they need neither AFVs nor glycol.

[JohnMo]

20 minutes ago, sharpener said:

I do not understand how Viessman can say they need neither AFVs nor glycol

They are silent on AFVs but say no to glycol and also state water shall be to VDI 2035. 

 

Couple of things with VDI 2035, it is pretty pure water, so maybe less in the water to initiate gelling or solidification of the water.

 

I have had drink outside since Christmas (water, beer, wine) We've been down to -10 with our any breakages or freeze up. It's near the house so maybe not so cold, but still pretty cold.

 

Plenty of good marketing going on, to convince everyone to add glycol or AFVs.

 

16 hours ago, ringi said:

The Viessmann "defrost buffer" is connected to the CH by a value that enables the buffer to be both disconnected from CH and the CH to be bypassed. When a defrost is pending, the heat pump 1st heat the small buffer (and nothing else) to a high temperature, then uses the hot water in the buffer to defrost the heat pump.  This results in the defrost not removing any heat from the CH system, so keeps radiators at a more stable temperature while the defrost is running.  

(This defrost buffer also contains an electric backup heater, so a defrost of the heat pump is always possible regardless of CH water temperature, CH volume, and outside temperature.)

10 out 10 for thinking differently with defrost 

[JohnMo]

Bit of a write up here on the Viessmann and Vaillant defrosting 

 

https://community.openenergymonitor.org/t/viessmann-defrost/27441/4

[MikeSharp01]

2 hours ago, JohnMo said:

https://community.openenergymonitor.org/t/viessmann-defrost/27441/4

Interesting read, makes you wonder why they don't all have the Viessmann feature. What I don't want is an litre tank emitting heat all the time outside the heating periods in the year so having that extra bit of volume only when you need it makes sense. I suppose you could implement it yourself, assuming you feel you need it - system volume wise, if you knew that a defrost was coming or perhaps by running both the UFH and the DHW circuits together when the defrost was on to maximise the systems volume.

[sharpener]

On 23/01/2025 at 11:25, Chanmenie said:

the buffer is there to assist defrost

 

22 hours ago, JohnMo said:

Bit of a write up here on the Viessmann and Vaillant defrosting 

 

https://community.openenergymonitor.org/t/viessmann-defrost/27441/4

 

@Chanmenie implied the buffer was external whereas the linked article says it is inside the outdoor unit.

 

I suppose it might depend on the size, there will be more free space in the 15kW version with its bigger fan and evaporator. But again you would not expect the one size - 16 litres - to be appropriate for all models.

[JohnMo]

5 minutes ago, sharpener said:

 implied the buffer was external whereas the linked article says it is inside the outdoor unit

Think it can be located in various locations depending on exact model and indoor unit purchased.

 

16L is about 0.6kWh which is equal to the energy used for defrost in the write up. Smaller units maybe don't heat up so high?

[JohnMo]

And a video

 

https://youtu.be/FohU-RNTA4E?si=4dBQdfkq4eXEVDXD

[Chanmenie]

3 hours ago, sharpener said:

 

 

@Chanmenie implied the buffer was external whereas the linked article says it is inside the outdoor unit.

 

I suppose it might depend on the size, there will be more free space in the 15kW version with its bigger fan and evaporator. But again you would not expect the one size - 16 litres - to be appropriate for all models.

With the Veismann 151 the 16L buffer is located in the indoor unit with the DHW cylinder.

don’t know if there’s another small one in the outdoor unit