jack

I've moved the other post to this subforum and will now lock the current post to avoid having two chains of discussion.

Your experience may have been straightforward, but I'm specifically responding to where you said "They are not looking to catch you out". I disagree, and I think it's important that people not get complacent or think that HMRC is on their side. A brief summary of the background and outcome is here. There's more detail scattered across many posts in the VAT sub-forums.

I find the SWMBO references interesting. We all have our relationship challenges and imperfections, but being told what to do by my wife isn't one of them. We tend to decide by consensus, partly because we're both decent people, but mainly because we're both so stubborn that there's no way either of us would ever allow the other to boss us around.

TBF, nothing your VAT man could have done would have saved me if HMRC had decided to rule that I'd claimed too late.

I'm not sure how much time you've spent looking through the VAT reclaim forum, but very often, they are very much trying to catch you out. HMRC not that long ago tried to apply serious penalties for fraud when someone accidentally tried to reclaim self build VAT back when they weren't actually eligible. They answered every question on the forms accurately, so it wasn't like they were trying to pull a swift one, it was just a simple misunderstanding. The tribunal who kicked HMRC's case out was livid at the way HMRC had behaved. They've randomly tried similar against people who've accidentally tried to claim items not covered by the self-build reclaim rules. There's example after example of HMRC pulling this kind of nonsense. Worse, the processes are extremely opaque. For example, I got a full refund with no questions asked, over 5 years after moving in to my place. There were long periods where no costs were incurred. I assume that a couple of late, biggish invoices helped me over their interpretation of "within 3 months of completion), but who knows? Maybe it's just who I got on the day. Whatever the truth, HMRC is not your friend, and people should do everything in their power to avoid giving them a reason to issue a negative judgement. Even if you're completely right, they'll drag you through an internal appeal process and then to tribunal, costing you time, money and stress.

Tell her it's too hard/expensive/disruptive to do now, and that you'll agree to revisit 6 months after you've moved in. If she still doesn't like it then, you should agree to change it back. I guess you're not that far off finishing, but I found our appetite for spending diminished significantly as the build went on. Perhaps she'll feel the same and won't want to spend £1500+ further down the track. Also, why did you make a decision like this without discussing it? I wouldn't dream of making a change like this without discussing it with my missus. Nothing to do with being scared of her reply, but I genuinely want both of us to be happy with the result. Probably explains why the house is still not properly decorated 6+ years after moving in!

Welcome @Solarexploits Looking forward to seeing your posts.

Yes. The manufacturer is pretty clear about positioning the 3 bar PRV after the softener, even if you don't have 6 bar incoming: My understanding is that if you have a 3 bar PRV on the incoming, then it's trying to maintain a maximum of 3 bar at its output - that is, between it and whatever restriction is downstream of it. In the scenario you set out above, the 3 bar provided by the PRV will be reduced at the softener's output, rather than maintained as you suggest. Assuming a nominal 0.5 bar loss through the softener, then the most you'll get at its output is 2.5 bar. My understanding could well be wrong though.

I'm a vaguely competent DIYer, but didn't have any building experience. The things I did myself (or with help from my wife and others) Installed the MVHR unit and ductwork (electrician wired up). Installed the UFH manifold (I'd have happily laid out the pipework too, but this was done by the timber frame company). Built up and fibreglassed two small balconies. Installed frameless glass rails and glass on the balconies. Installed eaves. Helped electrician with a lot of basic stuff like installing backboxes and conduit, and pulling through wires. A small section of larch cladding that wasn't finished for various reasons. Epoxied garage floor. Plasterboarded some of the garage. Put up some light fittings (especially exterior). Installed stairs.

You also don't want to short-cycle your ASHP. Ideally, you'd have some battery storage and accumulate enough energy to power the ASHP for some minimum period, but that's complicated and expensive. We have an immersion diverter and ASHP, and they play very well together. The immersion diverter allows you to store more energy, because it can heat the water above the maximum temperature the ASHP can manage. In summer, I expect that on many days the ASHP will have delivered all it can manage by 9 or 10 am. Using an immersion diverter lets me put a lot more energy into the tank.

Be careful to note your unit's installation details. I didn't check ours until long after the plumber had left, and his team didn't follow the instructions. If you have high incoming water pressure, then the trick is to put a first PRV before the softener to bring the pressure below the softener's maximum operating pressure, and then a further one after it to bring the pressure down to what the house is designed to operate at. For example, we have nearly 6 bar incoming. We should have a ~5 bar (6 bar being the max the softener runs at) PRV on the incoming main, and then a 3 bar PRV after the softener. Even if your pressure isn't that high, you should still put the main PRV after the softener, not before. Here's the picture from the manual: Unfortunately, we have only a 2(!) bar PRV on the incoming before the softener, which does leave us with sub-optimal water pressure if there's a shower on, the washing machine is refilling, and the water softener decides to regenerate at the same time. When I asked why they installed such a low bar PRV, I was told that they wanted to make sure the water pressure didn't look too powerful if the building control guy turned the taps on!

I really like this take.

Thanks so much for that link. JFC those are some unpleasant houses.

We have 28mm Hep2O connecting our ASHP to our plant room over a ~9 metre distance. All done without a single join, which in our case would have been a massive pain given a lot of it is in a channel cut through our underfloor EPS. Hep2O barrier pipe includes an oxygen barrier and is specifically designed for this sort of application, so I can't what the objection would be to its use - from https://blog.wavin.co.uk/all-you-need-to-know-about-hep2o-push-fit-plastic-plumbing-pipe/:

I suspect you're right. The only time I've ever seen mould in ours was when we had some issues with condensation buildup. It was in a patch on the heat exchanger, and it was a nightmare to clean even though it was just along an edge. That said, I understand that many of these units share a heat exchanger, so with luck it might be cheaply replaced if needed.

Claim for the total if delivery is on the same invoice. We converted to GBP using the historic daily exchange rates on xe.com. Might have perhaps been able to show the actual amount paid in GBP by digging through credit card statements, but that seemed like far too much faff for the amount it would return.

MBC offered to engineer our joists to take a 50mm poured screed and I'm sure it wasn't that much more cost-wise. The real cost would have been getting the screed done.

According to the posi joist technical handbook, holes and notches are forbidden, but fixing flooring and strongbacks etc is allowed:

I recently looked into drilling a small hole in an existing posi joist and all the evidence suggests no form of drilling or notching is allowed. Have you checked this?

Never heard of this before, but the wikipedia entry for Portland has this:

I described what happened in this thread: If you don't fancy reading it all, I'd say the main takeaways are to make sure you use proper fixings (eg, not plasterboard screws if you're using a tile backer board), and lots of them, and don't butt boards up hard against each other.

If you demolish to the foundations leaving no more than the facade standing, and this is a planning requirement, it can be treated as a new build for VAT reclaim purposes: see section 3.2.1 here I seem to recall that this is treated very strictly, so you need to be careful about how you go about it. Personally, unless you have no other choice, I'd nuke the lot and start again.

You can upload it to YouTube and post the link here. Use a throwaway account if you want to increase your privacy somewhat.

Welcome to the forum. That's very unhappy-looking MVHR system you have there! How long did you leave the MVHR system turned off, and how have you been ventilating the house during this period? How was it left with the supplier? Did they advise what you should be doing while waiting for parts? It also seems odd that no effort was made by them to identify exactly what had gone wrong. I genuinely have no idea whether the unit is salvageable. It's possible that you can clean it out and disinfect it sufficiently that it can be used again, but getting at the insides of the distribution pipework in the rest of the house may be an issue. Do you have a semi-rigid system? If so, is it circular in cross section? It's possible that with a lot of time and energy you could clean and disinfect the insides of such ductwork (I vaguely recall someone once talking about duct cleaning a few years ago), but it may not be a job you can do yourself.

We have exactly the same. We have never set foot on the balcony off our master bedroom, and the one off my older boy's is similarly unused. They do look nice though, and the overhangs provide some shade in summer. Shame that they collect leaves and need cleaning periodically. Couldn't agree more.