PeterW

So a structure of drinking straws inside I now get, but how you would support and seal that whilst still maintaining flow would be a challenge. I’ve built a couple of contraflow copper heat exchangers and they are hard enough as you can pressure test them to find leaks ..!

Yes it needs sealing and I would always buy that stuff online as it’s a specialist product. Most roofers struggle with the air permeable membrane without adding other problems ..... quick tip for doing your tape - create your 150 overlap but don’t tack it down. Put a piece of board above the overlap and turn the fabric back onto it, apply the tape and push down and then remove the backing, folding the overlap back onto the fabric below... Quick and easy and means you can get some decent pressure on at least one side of the tape.

The room has a minimum fan size / extraction for building regs and you have that big F/O body fan that will over power anything in that room ... I can’t see any value adding any MVHR to the setup currently, other than a basic wall mounted one that will have much greater efficiency in a smaller box. Air to air heat exchanger membranes are measured in microns not millimeters for good reason - to maximise heat transfers. Thick pipes would be ok with a water to water heat exchanger but still, it’s not ideal.

Drain pipe has 1.5mm plastic wall - heat transfer would be negligable.

Use 68 and fit more..... ?

You can get nice 68mm soffit vents that fit neatly into a standard downpipe connector so you can use cheap downpipe, couple of elbows and jobs done ....

Ideally it needs to be insulating so a lot are foam or lined with foam.

You may find a mortgage company need evidence of build insurance - I know the Melton BS do.

For what ..? The enclosure for a heat exchanger ..??

Thats crossflow - counter flow is where the air flows are parallel and this is much more efficient.

If you mean the Correx type stuff it will never work as it’s just too thick and does not have a guaranteed sealed channel structure. Airflow between the layers is what causes the heat transfer - aluminium is used a lot where you have a large heat differential such as in condensing tumble dryers. In an MVHR heat exchanger the temperature differential is so low at 5-10c then the film thickness is reduced to 0.2mm or thinner to ensure heat passes between the air flows. In in its simplest form, a cross flow heat exchanger has the two air flows at 90 degrees to each other, in a counter flow the two flows are parallel but flow from opposite ends.

Just on this, you shouldn’t be relying on the tanking to stop water getting through - it’s the absolute last line of defence ! Tiles and grout are reasonably waterproof - just look at a swimming pool for example. A full bed of adhesive is also pretty watertight, so with tiles, grout and adhesive, any water getting through will be minuscule and the tanking is there to provide a final layer. Be aware that the Aquaseal stuff doesn’t look like it’s fully covered but you put it on in two layers at right angles with a brush and it does work well. Don’t be tempted to put it on too thick or it will flex and the grout will move.

Tanked = adhesive Untanked = silicone

You can also cut the flat sheet into strips instead of using it around the valve ...

Your best bet is to leave it and let it establish naturally as otherwise you will be watering daily and probably going through 2-3000 litres a day. If you’re desperate to water it and keep it looking good then try these guys - always had good service and they know their stuff with irrigation equipment.

Ikea do a full range of built in stuff and all of it has a 5 year warranty. John Lewis can be surprisingly good value too - their own range stuff is rebadged AEG but with a longer warranty.

Use that adhesive you bought to fill the gaps and put a fillet on the shelves

I’ve found site insurance to not be too badly priced for what it is and taking it over a year it’s worthwhile doing the whole rebuild cost up front as some won’t insure you part way through.

I'd pull the gauze on that Y Strainer too and see whats in there

I'd use Cement board or something similar

Seems very cheap for 12 months..?

How much hired in cover have you got on that..? It seems very cheap, or is it just covering public liability and employers liability..?? How much have you got for build cost..?

Think its about £22 for 15 litres but covers well at 2 coats

Polystyrene is a plastic... EPS or Expanded Polystyrene is the insulation that everyone is aware of - the small white balls are polystyrene blown with a gas - nowadays they are CFC free but used to be blown with all sorts of weird stuff.

Getting a rod around a swept bend at the foot of a stack would be a challenge, and once used, I wouldn’t want rods coming back into the house ..!! Other issue is buildup - if your blockage is at the foot of the bend on the junction, opening a rod point on a vertical stack with a WC above you will be........ interesting ........