PeterW

Interesting one ..! Got some very low wattage lights to be installed into a wooden retaining wall. The lights are 85w x 45h x 55d and sit inside a sleeve - actual light is IP55 and has small glands for water penetration from the back of the units. The question is what to run to them as they will be powered from the back with the cable running approx 300mm below ground level along the back of the retaining wall. A very thin armoured would be preferable but would need gland / adaptable box every 1.2m which would make it quite expensive to do for 8 of them and finding 0.75mm armoured 2 core is a challenge. SY has been suggested but I think it would have to be run in conduit, but wonder if at that point just running H07RN would be just as quick as the conduit provides the protection anyway. Thoughts ..?

It’s not - there is no way I would let a PM choose the fixings for a ring beam..!! It is about understanding of the interface spec and who is accountable where - and that’s down to how the specification and designs are done, which surprisingly is why the PD role is so important. This is why the frame companies end up with as @Nickfromwales called the “by others” lists and that is where the problem occurs as no amount of onsite PM will sort a badly written spec when the shovels hit the ground.

Just been back and checked and the old business insurance we had precluded us as acting as either principal designer or principal contractor for the purposes of CDM2015. From memory it added about 30% to the premium to hold those roles. I’m pretty sure that any self build insurance will also remove them - there are certain things you just wouldn’t know as a designer / contractor

All contractors should carry their own first aid kit - you can open another box of liability worms when you start providing first aid although there is a little bit better protection in law for a first aider !

Last one I saw there was a near Mexican stand off between the frame installers and the foundation team about who was responsible for the timber ring beam and how it was held down…. Which is kind of fundamental ..!

because at 5°C one pump is fine !! And you have got inequal flow through the pumps as they haven’t been properly balanced and doing parallel pumps is a really bad idea !! ok that sounds worse than before !! It should be a single pump on the return (they last longer, it’s cooler) but what I can see from what you’re saying is that you have variable flow depending on the destination of heat. single ASHP, pump on the return and wired properly for W plan, this will all work much better than you have today.

@ProDave read my explanation - I doubt the way it is set up it will deliver 13kW. It should have 2 pumps and a set of non-return valves.

Circulation pumps not heat pumps - where is the circulator in the house ..? Right … I think you have a flow issue and what’s happening is that one pump is doing most of the work - they aren’t piped in tandem from that picture they are in parallel. What should happen is that one does the first heat input (say 25-30°c) then the second then does the uplift from 30°C up to the set temperature. What you’ve got is a single circulator pushing into a pair of heat pumps and it will favour the one with least resistance - if one is cutting out then I would think it has low flow through it and is seeing a set temp before the other. A single 16kW heat pump would make it a lot simpler and I would think you’d get a lot better function from it.

Actually these were rebadged by Ideal - sold as secondary to a boiler http://www.gasapplianceguide.co.uk/Heat Pumps/Technical Info/Airtherm User Manual 1.pdf @ST3VE78 where are the pumps installed in the diagram you’ve got as there is only one shown..?? Are they on the supply or return..?

@ST3VE78 from memory those calorex units have a built in pump - is there a Y strainer anywhere in the system and have you checked if it’s blocked ..? Also worth checking the pumps themselves as they could be running very slowly and increasing speed may help Also worth getting hold of 4 cheap digital thermometers and putting them on all 4 of the buffer pipes at about 1m from the buffer itself. have to say though the units look on their last legs !!

+1 to this Screed can take the camber out of the beams and can be graded with a long board to run to a drain point and then membrane or waterproofing liquid over the top. The slabs on pedestals can then be laid level as any water is draining below them.

Doubt it as they are pretty old units - rated at nominal 9kW but at 0°C that drops to 6.5kW so by -5°C you can reckon it’s about 4.5kW or 9 for the pair assuming they are tandem.

So did you use bare minimum insulation at the time ..? As that may be your issue. UFH won’t do better on gas at 35°C flow rates as it will short cycle unless the buffer is set to do long burns with multiple stats to control call for heat. Start again with a heat calc but if it adds up I would stick with a new ASHP (sounds like a 16kW or similar) on R32 for the DHW and you should be fine.

Providing a toilet is one thing; providing HSE oversight with full accountability for site safety with a full set of RAMs and policies is something quite different !

Which is fine if there is a designated main (or principal) contractor however under CDM2015 if you’re the main contractor on site at that point - ie have total control of all operations, then you are deemed the main contractor for the purpose of CDM 2015 and by the HSE. From the HSE website : If a domestic client does not appoint a principal contractor, the role of the principal contractor must be carried out by the contractor in control of the construction phase. So for this to not be correct then the contractor should have an explicit clause in the contract that requires the client to act as such. I would be interested to see where that is highlighted in any Potton contract as I’m not sure how HSE would see it being passed to someone with no liability or training in safe working practice.

That I didn’t question - it’s the standard SIP/Panel design that hasn’t changed pretty much since it’s original inception and like most SIP systems contains inherent flaws which are widely documented. Pretty much every TF company does design / regs drawings and submissions so it’s not exactly a ground breaking service.

Comfortably above ..??? Standard spec is 0.02 above BRegs for walls unless you pay more, they also do not guarantee Passiv as they do not do full turnkey as of now. Whether they will do in the future is suspect as they are still only using subs for certain aspects with no overall package offering. part owning an M&E and services consultancy that specs and installs for architects and builders - so have first hand experience of the standards in a fairly broad range of companies including Potton (in 2020/21 most recently). Hence my comment that there are better ones out there !!

this.. and.. this.. Potton are the main contractor under CDM2015, you are a domestic client. Under CDM2015 the main contractor holds the responsibility not you - if Potton are telling you otherwise they need to go and re-read the regs …

There are a couple on here - Potton was bought by Kingspan a while back and they haven’t advanced the designs much other than to keep in line with building regs minimums. There are many better TF suppliers out there.

Get a new surveyor ..?? Photo 7 isn’t defective mortar on that chimney, it looks to be a substantive crack plus the outer edge is leaning suggesting the stack needs a strip and rebuild. Breaking off on the back of old rosemary tiles is not unusual but the whole lot is looking tired. Would suggest 1920’s or 1930’s roof that would be better replaced however you say there is a party wall and stripping and redoing rosemary roof joints between houses isn’t the easiest to get right.

Spanish company that uses a mix of German and Italian parts although I am sure they are assembled in China now. Used to make some good pellet boilers - looks like they are expanding into the renewables market. @drcarrera have you had a proper heat loss and heat design done as 20kW is a lot of heat demand.

Doubt you’ll get perfect 11mm base and most spreads will hit the door linings if that’s what they can see. Also check your 132mm casings as I’ve had them as thin as 128mm and as thick as 138mm depending on supplier. I don’t like planted linings either but that’s just preference

Yes would be fine as the compressive strength of the insulation and the jointing of the floor would spread the load across a wide area. 2 layers of 18mm bonded and screwed together is going nowhere fast !

@CalvinHobbes too many variables unknown ..! House size, bathrooms etc..? Also, C-19 isn’t an airborne transfer virus so filters for that are irrelevant - finer filter will help with pollen etc for allergy sufferers but the finer the filter, the more often it needs cleaning/replacing.

I think that’s an autocorrect of grilles …?? Or do you still have bars on the windows of the current bedroom ..?