willbish

Great to hear. Cant wait to do the same in our new place, my current flat is shocking. Only 5 years old, adequate standard of insulation but the decrement delay is terrible. The natural ventilation is quoted to be 5.0m3/h.m2 but I think its much lower than that. We cant fully open the windows until the 2 year old is in bed because he'll climb out! Mechanical ventilation needs to be mandatory on new builds IMO. Anyway here's to a chunky slab!

We have reached a workable solution today. No ring beam or slab thickening in any areas, which means I get 300mm of insulation under the whole slab. But as a compromise a 300mm slab throughout with, as yet unspecified but, 'significant' amount of reinforcement! What did @PeterW say about a serious heat sink! How much heat is this 30m3 slab going to hold ? The extra 50mm shouldn't affect my levels too much, everything so far has been buried deeper than necessary. I will have one run of 110mm storm pipe in the bottom 50mm of type1 layer however, assuming that can be left as is?

I don't have the luxury of employing two engineers. I'm working with a recommendation direct from Isoquick so should be getting the most appropriate design.

Agreed, will raise this point this morning. Isoquick uses the same grade of insulation throughout

@PeterStarck that would be very helpful thank you. What you've described is exactly what I want/think is appropriate

Thanks @JSHarris your figures and dimensions are much more in the region of what I was expecting. I'm not too fussed about the 250mm slab thickness over non loading bearing areas, it is the common design with Isoquick. My understanding of the Isoquick system was the thicker 250mm slab throughout would compensate the need for a ring beam/ edge thickening therefore allowing 300mm insulation throughout. I have already asked the SE if anything could be done to reduce the slab thickening, his reply was no. I asked him what ground bearing he would need to scrap the slab thickening. His response 'somewhere in the region of 100kN/m2' Hence returning to the ground investigation chap. Just to add to the pressure, I've being told if I don’t approve the draft plans on Monday the SE will not be able to finalise next week before going on holiday for two weeks! @PeterW Yes to UFH. The SE has specified thickened strips as well much like @jack so the thickened area is now 25% of total slab area

For those with an insulated raft foundation, what was your ground bearing capacity figure? And was your raft designed with extra thickening? My SE had made noises that my ground bearing figure of 50kN/M2 is a bit low but workable. His latest design of the raft has 25% of the area thickened to 400mm and in these areas insulation reduced from 300mm to 150mm. This feels like a big step down in thermal performance to me, but perhaps I shouldn't be so concerned. During the ground investigation I was told that I had ideal ground for a raft so not sure how a 50kN/M2 figure has been derived. I've asked the GI chap if he could revisit his Standard Penetration test results with hope to increasing the ground bearing figure; no response yet. I also feel the SE is being over cautious; he has the slab edge thickened where a single story porch will be. That seems really unnecessary.

Have you had a go at Tadelakt? I like that Moroccan look for bathrooms but wonder how water repellent it really is. Again too expensive I reckon

You could consider a clay plaster to save on the decorating... I just had a quote from Clay Works, 226m2 material only £9063 ?

I would be very interested to follow your progress, please keep us updated. I as alluding to Brine heat exchanger like @Barney12 has installed. Geothermal i think is an incorrect term. Has anyone got something like this plumbed into their ASHP and MVHR unit and using it for cooling? Would the effects be that noticeable?

This is interesting, @JSHarris could you elaborate a bit more please? I liked the idea of a brine geothermal heat exchanger for the MVHR but struggled to justify the additional cost. The idea of a duct cooler seems simpler and cheaper, would your ASHP be able to keep up with MVHR flow rates to provide the 12°C input air you mention?

Has anyone adhered to the Part M requirements for their outside sockets? Could a jobs worth BC inspector argue that a patio area is deemed to be a habitable room?!

That's what I've opted for, seems sensible to have the redundancy if the heat pump goes bang in mid winter

Because an ASHP could charge your PCM34 (DHW preheat) with 3/4 times less electricity than using the grid when the sun aint shining.

A DC array or a mixture of AC fortified with DC is something I am exploring and would like this option to be kept open for my SA units. Very keen to hear more info when it's available. Cheers

No probs at all. I understand Sunamp are going through a busy period, and long may it continue. I've got a quick question regarding electric immersions, as @Nickfromwales mentioned earlier 3kW immersion is actually 3x 1kW. If I want to power my Sunamp with DC solar PV should I request one or perhaps two of those immersions to be DC compatible? Thanks

@AndyT I appreciate you taking the time to answer questions on the forum but please would you be so kind as to confirm receipt of my order and money which I sent to you last week. I made my order on the 27/06 and electronic transfer of over £5k. Since then I have sent two emails both unanswered. I spoke to you on the phone today just before lunch. You said you'd be right back to me. I have at times since last Wednesday wondered whether I have been the victim of a hoax. Or at best wondering what the post sales service will be like... I'm only asking for a simple confirmation that money has been received, perhaps a small thank you. Really didn't want to post publicly but don't want to wake up for another morning wondering if there's a small possibility I might've been scammed!

Spacer + mesh + pipe <50mm?

The DNO says that after the upgrade only 4.0kWp is permissable. Before the upgrade zilch. My offer to limit the export to 16A was refused. So I was thinking that anything on top of 4.0kWp would have to be DC. Happy to be a little inconsistent with the truth if that's what you're saying but might struggle to persuade my sparky

You think I should just settle for 4.0kWp, what about my slightly irrational desire for loadsa PV Is a duel AC & DC system worth the extra configuration hassle? Will a sole DC system lead to a waste of excess generated electricity if I don't have additional storage on top of the Sunamps

Had some futher correspondence from the DNO, I told them I would be installing a large electric combi ~14kW Asked if I could limit PV export to 16A Their response: Hi Will I’m sorry that you were unable to reach me yesterday, I was out of the office all day. As the area is quite rural the number of customer’s connected to the transformer is very low and therefore the load being pulled is insufficient to counteract the voltage rise caused by your PV. That said, if you were to install only 16A per phase of PV you could do this by the fit and inform process whereby you simply notify us post-installation and therefore it would be up to Western Power to pay for any reinforcement costs. I have done a study on a 16A installation and it would actually only require yours and your neighbours service cable to be upgraded. We would do this free of charge. If you are installing an electric boiler this is classed as a disturbing load and we would need to conduct a network analysis on this also. I have attached the relevant form to be completed with regards to the boiler. Unfortunately any reinforcement costs associated with this installation would be chargeable to you. So to clarify, with regards purely to the PV, if you only install up to 16A per phase of PV we will cover any reinforcement costs. This 16A applies to the whole installation, not just the export. I hope this makes sense, please do not get in touch should you have any further questions. Kind regards (the do not get in touch bit has not been edited by me! ?) So at least I can have some PV. I've got space for more than 4.0kWp though, what are my options now? -Standard 4.0kWp MCS system -Diy 4.0kWp system -Either of the above plus additional panels on DC configuration -Whole array DC Any input much appreciated

Will quiz the DNO on this and let you know their response. I am also awaiting a quote from them to bring the supply in through a duct. Have also asked for a 3-phase quote, reckoning that'll be crazy money judging by their perceived state of the local infrastructure.

I like the sound of this, greater efficiency, cheaper install cost as no inverters required. Would be concerned about over sizing the array. With storage (sunamp) up to capacity too early on a bright sunny day and potential generation being wasted. And therefore increased payback time of the PV hardware. I was expecting to size my array based on limitations of roof area first, then amount I could afford, then any DNO limitation.. Think I'm going have to give this some careful consideration to get it just right. So if I only have a DC set up what else could I power once the Sunamp is topped up? I guess nothing domestic other than an electric vehicle, which is probably a few years away for me. Even then would I need two charging stations..

Well they certainly aren't getting 10k from me This might be an avenue worth pursuing if I wanted a free upgrade. I will be having an ASHP but i doubt it'll cause a significant voltage drop to concern the DNO. Do I really need an upgrade I dont want to export any of PV anyway so is all of this a bit pointless? Can I just get on and DIY install as much PV as I can afford and have a way to satisfy the DNO that nothing will be exported?

I made a G59 application with my local DNO to test the water and see how much PV they would let me install. Their response pasted below. My solar guy thinks that if I limit my export to 16A per phase then the DNO may be required to provide the infrastructure upgrade for me. I don't read it like that. Has anyone experienced this before? The 16A per phase is this a discretionary maximum, can the DNO prohibit any generation and/or export? And does it all really matter if i go full DIY and ditch the MCS What equipment would satisfy the DNO that anything generated is not exported to the grid? Good morning I have been passed your application for PV Installation at Unfortunately there is currently no capacity for generation at this site without considerable reinforcement works which would be chargeable to the customer. Not only will the customer’s own supply and their next door neighbour’s need to be renewed, but a significant stretch of the overhead main will also need upgrading. For clarification this is due to the fact that the overhead conductor is relatively small and also the loading on the network in this area is quite low. The combination of these two factors means that the volt rise caused by the installation of any generation would, at this stage, exceed the permitted limits. Upgrading the conductors to larger ones would enable us to overcome the issue and I can produce a quotation for these works but would advise that it will be roughly in the region of £10,000. Please let me know if the customer would like to proceed with this and I can cost accordingly. Kind regards