Replacing DHW tank mandatory for BUS?

[JamesPa]

On the general topic of 'good enough' to simplify/de risk/reduce price of installs, I have just suggested to an otherwise cooperative and flexible prospective installer that I keep my existing DHW tank and run the HP at say 65 (or even 70) for heating the DHW (it will be run at 45 for CH).  The claimed cop at 65 for the Daikin unit in question is over 2, and DHW is a small proportion of the total consumption.  

 

He point blank refused to not replace the DHW tank, on the grounds that he has got into trouble in the past with the BUS people for not doing so.  When I interrogated his reasoning he was adamant that it was BUS related.   He has already accepted that a pre-plumbed cylinder is not feasible, so his real reason is not that he employs idiot plumbers who cant cope with anything other than a plug together system.

 

I read both the MCS and the BUS legislation and cant find any material reason why what I have suggested is not legitimate.  I fully accept its not necessarily 'the best' and may well do a DHW upgrade in the future, but that's not the point

 

Is the installer just giving me a load of BS or does anyone know of a genuine reason that the BUS mandates replacement of the DHW cylinder?

Edited July 21, 2023 by JamesPa

[Temp]

I had a quick look at the regs on what counts as a BUS heat pump and it says...

https://www.legislation.gov.uk/uksi/2022/565/regulation/9/made

 

Quote

 

(2) A heat pump meets the suitability criteria in relation to the eligible property, or a property to which regulation 14(1)(b) applies, for which it is installed where—

 

(a)it provides heating—

 

    (i)solely to that property, or to both that property and any related property, and

 

    (ii)for the purpose of both space heating and hot water heating, using liquid as a medium for delivering that heat,

 

(b)it is capable of meeting the full space heating and hot water heating demands of that property, and

 

(c)it replaces the heat generating components of the original heating system installed in that property (where applicable), other than any—

 

    (i)supplementary electric heater, including any immersion heater,

 

    (ii)circulation pump, or

 

    (iii)solar thermal collector.

 

 

So if you are allowed to retain an immersion heater surely you can retain the tank its in?

 

 

[Temp]

Try this guide for installers...

 

https://www.ofgem.gov.uk/sites/default/files/2022-05/Boiler Upgrade Scheme Installer Guidance.pdf

 

Table 2 page 23
 

Quote

 

Other parts that can be retained 

 

• Container and fixings

• controls

• pipes

• emitters (eg radiators)

• night storage heaters

• hot water cylinders

• buffer tanks or thermal stores

• expansion vessels. 

Edited July 21, 2023 by Temp

[JamesPa]

11 minutes ago, Temp said:

So if you are allowed to retain an immersion heater surely you can retain the tank its in?

That seems logical 

 

6 minutes ago, Temp said:

Try this guide for installers...

 

https://www.ofgem.gov.uk/sites/default/files/2022-05/Boiler Upgrade Scheme Installer Guidance.pdf

 

Table 2 page 23

I'll check this out.

 

MIS 3005-D could be interpreted to require you to insulate the primary feeds (ie take up all the flooring including any solid flooring) if you retain the dhw tank, but not if you replace it, which is perverse.  I have asked MCS for clarification, if they confirm the perverse interpretation then... well I'm hoping they dont