Improving insulation to suit an Air Source Heat Pump - what are you doing?

So I presume that Retrofit aren’t expecting that they will be paying for your MVHR out of the £5000 insulation allocation for each house?!

The heat-exchanger unit itself for a “whole-house” installation would typically cost around £1100-£1600 depending on the quality of the fan motors and the exchanger plates.

 I’ve added an additional radiator within my unit with water fed from the same thermal store outlet that supplies my underfloor heating.

The 150x150mm mini radiator is normally used by PC gamers for their water-cooled processor chips and graphics cards. I screwed it inside the heat-exchanger case immediately before the outlet supplying fresh air to the house. The input/output ports take ½-inch flexible hose which run through a couple of rubber grommets in the side-wall of the enclosure.

The main cost of a whole-house ventilation system is the running of the pipes themselves. Without taking up floorboards to work out how the pipes might be inserted I don’t see how it’s possible to give a price estimate.

Beware that many firms leave the pipe-runs to be installed by the most junior member of the team. That means he/she may not appreciate the need for:

• sufficiently air-tight seals between joints
• rigid (not flexible) pipe where possible to maintain pressure
• adequate insulation around all pipes, especially at bends
• the use of round pipe rather than rectangular to reduce noise
• no pipe joins within 4 pipe-diameters of an outlet vent
• not sawing through the odd joist(!) to reach a tricky location

And that’s why I’ve installed everything myself so I know it’s optimal!

@Tim_OVO  do you want to lift this post into the main open Forum?

Haha !! that would be good wouldn’t it !!! No. The £5000 insulation allocation (if it was actually divided up like that - news to me) has all gone on the heat pump, radiators, cylinder and many yards of plumbing - plus the hours of work needed to install it. Their report included information like this, ie further works that could be done in an ideal world. We’re not living there are we?

There should be an additional-works budget for each house beyond the actual heat-pump hardware and its installation.

Most of that would likely be allocated for upgrading insulation. But whatever it’s spent on, it must be accounted for. The final report to BEIS will be almost useless if it doesn’t show what additional work was undertaken - including extra stuff paid for by the homeowner.

@Transparent would you consider my warm air ducts could be repurposed for MVHR ?

Yes of course. They’re bigger than the 100mm most commonly used for MVHR, but that shouldn’t a problem. The slower the air moves through the duct, the less noise it makes.

@Transparent you read my mind! But this great info is in amongst a thread that’s specific to the trial. You might consider copying and pasting the good stuff into a new topic which we can post here…..?

Done. The basic shell is here.

I’ll add a header-image and a couple of diagrams later. But at least Trialists here can now direct others to the relevant topic on the open Forum.

update on the chimney… the ‘sheep’ has been installed with a new sailor’s hat chimney pot ! No more draughts.

This topic is now in the public Smart Home category and ready to help anyone interesting in decarbonising their home’s heating with a heat pump. 

Please be advised, some comments in this thread refer to trials that OVO are involved in, with households of a trialist getting an air source heat pump. We have a private forum area for trialists to discuss their heat pump. If you’re a trialist and you want access, let us know here: