DIY install

[eandg]

Any tips? Would or would you not do it again? We are likely to be going with BPC - only concern is they don't have just given us a bog standard design and said 'you work it in with your joists' albeit they give us additional ducting to account for any waste which adds an element of risk. 

[Andehh]

I almost DIYd it myself (my other thread from the weekend) having spent some time on YouTube. If you have webbed joists and an extra set of hands, I really don't see it too complicated. Commissioning being trickier, but something that can be figured out further down the line. 

[LA3222]

I installed myself, it's easy enough to be fair. I had to pay to get it commissioned as BC moaned - cost about £300. I look at it from the POV that only spending £300 still saved loads on the labour and it was actually worth doing I think - watching him wandering tweaking the valves and checking flow seemed like a PITA that I'm glad I didn't have to do.

[JohnMo]

I would do Fresh-R, or similar, if I ever did it again.

 

Hardly any ducts to run, on demand ventilation, reduced number of air changes, if the house doesn't need it.

[jack]

The mechanical side of our MVHR installation was one of the very few things we entirely did ourselves. It was extremely easy. 

 

We had a layout from the supplier, but when we went to do the installation we realised that the open-web joists allowed much shorter routing in some places, by going on the diagonal.

 

In terms of tips, I'd suggest making sure that there are no "closed" routes. We had a minor scare when we realised all supporting joists around our stairwell were solid, even though half of them were shown as open-web on the plans. Thankfully, the savings we made pulling some of the runs on the diagonal left us with more than enough to take a slightly longer route around the stairs to reach the affected room.

 

For pulling through the ducts, you really need two people, as they tend to catch on edges of joist webbing.

 

Where your ducts join the manifold, you should ideally have a reasonable length of straight run beforehand. That is, don't have a duct bending right before the manifold. It makes them harder to join to the manifold, and can really obstruct the paths of adjacent ducts.

 

Think carefully about whether manifold position can reduce your runs. In our case, moving the manifolds by a few couple of metres saved us multiples of that distance in ducts, because nearly all of the runs went in the direction we moved the manifolds. For example, if you have 10 ducts coming out of a manifold and they're all going in the same direction, moving the manifold 1m in that direction saves you 10m of duct. You might not have the option to do that, but we had the space and it worked well.

 

Think about how you're going to support the ducts, as they shouldn't have significant dips along their length. It can be as simple as some offcuts of wood bridging wider gaps, and/or using something like leftover breather membrane screwed to something above to provide support.