PeterW

Without seeing the state of the roof timbers, £400k is a tidy budget and could be achievable. First stop would be a structural engineer, and someone who does decent modelling of what’s possible - consider a steel portal frame inside the existing building for example and keep the outer as a decorative shell. it’s not listed is it ..???

It’s the PM (project management) time. What are they doing for that ..?? Industry standard is 15% PM time of overall Labour on that sort of thing - count the days to do all the “work” and then take 15% of it to be reasonable. Really ..?? Not seeing £100/M floor finishes or anything in your spec ..? That should be pretty achievable (given the £50k automation stuff) if done right, especially with the spec on the roof tiles etc.

£2.5k for 2 IP cameras and an NVR..???!! I’ll do it for £1.5k, and I’ll even get the cameras colour coded to match whatever nail varnish Mrs Puntloos requests… 20 days PM for installs ..? They are having your pants down ..!!

Big tiles ! What are they.? Ceramic or porcelain ..?

Agree and disagree - if I ask for a specific slump on the spec then I expect it to turn up like that, and if it doesn’t meet spec (ie it’s too stiff) then that suggests I should send an 8 yarder back to the batching plant ..? That would be an interesting discussion … Its also marketing bo**ocks words - they don’t actually have answers so they use the “as much as” and “potential” “possibly” and “up to” which means they don’t actually know. Given the slump is pretty much the standard water/cement ratio, on a standard gen/c25 mix going into floors and foundations you would hardly notice the difference. On a bridge it may be a different matter.

Not really. You can get lightweights for 95p a block and I’ve seen them quoted at £1 laid so it’s not stupidly low. C2 is much cheaper when you look at it, but is miles off (over double) on the lighting and electrical. You need to ask why - and also why are you spending £60k on lighting !! You may be better with a contractor to watertight and then subs on the rest.

Standard 170mm topup Roll is £24 from Wickes - average loft that is 8 rolls, and it’s as simple as start in the far edge and just unroll as you go. https://www.wickes.co.uk/Knauf-Insulation-Space-Standard-Top-Up-170mm-Loft-Roll---6-47m²/p/109450 Don’t forget a decent mask, and don’t forget to leave gaps at the eaves for airflow. Finally, make sure any hot water pipes in the attic space are insulated, big slab of PIR over the hatch and then airtight strips on the edges to make sure it’s all toasty. Fit and forget, and not a piece of technology required and all done for change of £250 and a Saturday afternoon.

Up the size to 160mm and you can have no fall …

Can you tell us what he stated and also his qualifications or background ..? highly unlikely (and it’s actually a natural gas / hydrogen blend in the tests, not LPG) and WB spend millions trialling lots of things. They trialled CHP for a while and that went nowhere too. couldn’t agree more …

That’s crap - I expect they have applied tolerance at their end in the system. It’s why I always ask for the job sheet to approve with the actual sizes on it as their design systems can do this automatically.

If the tank has an immersion I would just use that - leave the coils capped but the top cap just drill a small hole in the cap to allow expansion. That allows you to go back to adding ASHP in the future. The dual Willis circuit is overkill but yes, would require a PRV and also an overheat stat on each Willis.

How are you keeping leaves out of the system …? Shoe/grill can be used as can inline filters at each gully, essential really if you have trees around.

Standard CAT plug will fit through a 12mm hole, 5 cables will go through a 20mm hole. Cable Monkey do them in 10 colours, can’t think why you would need that many but they aren’t expensive. https://www.cablemonkey.co.uk/rj45-network-cables/12-cat6-rj45-patch-cables.html#/17-color-orange/61-length-3m/3295-boot_type-lsoh_with_latch_protection_boot At lengths up to 20m I can’t see why you would need to use cut cable

No idea why people still try and run and terminate their own Catx cables as there are lots of pre made, screened Patch cables available that are suitable for this purpose in lots of lengths for pennies. You can also colour code them for different things (red - PoE cam, green - TV points etc) and they are quick to run and there is no painful krone panels or other stuff required. Unless you are running UHD multiplex screens from remote servers, you will never get anywhere close to the limits of Cat5, never mind CAT6 or fibre. I’ve seen 250 contact centre agents running voice and business apps concurrently on significantly smaller connections than people are taking about - Virgin Gigabit fibre for example is a marketing gimmick and your upstream speeds are only marginally better than anyone else on copper .. Rant over …

So don’t forget these calculations are cylinder loss only, and assume the tank is kept at a constant temperature. In reality the losses are less as the tank cools by usage (and loss) and the bigger emitters are pipework losses. Also the heat is not “lost”, it is transferred to the air and the house so reduces the heat load in the winter so beware trying to calculate how much it is costing as it’s not simple !!

Use an insulated slab - 15 tonnes of concrete is an excellent way to load shift your heating requirements. The deltaT between the stored water / PCM and the air temp will be lower than with a conventional gas boiler so if you’re planning to try on doing this with radiators you may need a couple of Sunamp units as a minimum - consider that in your cost equations as it may take 8-10 years payback on the current energy prices. If this is a new build have you not considered increased insulation levels to reduce heat requirements ..?

But again this is down to BS7291 Class S and the use of the 3 factors as quoted previously - keep the temperature lower than 60°C and ideally use occupancy / time based circulation and you don’t have an issue regardless.

@Bonner here you go. I quoted Wavins own technical note. You basically run the UVC blended temp (~45°C) and you don’t have a problem. As @dpmiller says, this is about commercial ring systems that use local TMVs and circulate hot at 70-75°C

We’ve discussed this before and I quoted what Wavin told me back then. You also need to remember that your central heating will be running at a higher temperature for longer, a circulation system will be fine. he’s guessing ..! PEX and the likes are guaranteed for a minimum 50 years, mostly it’s lifetime.

Your problem will be comparison pricing - some things are unique to each building due to quantity, complexity of site, access, distance to supplier etc. I know for example that concrete can vary by 20% around here due to location and distance to the plant. Post up what you want but some of the values may be subjective.

without the model number I had to guess the generic Megaflo indirect installation manual.

Looking at that cable he hasn’t even wired it correctly. All the white connections should have wires in them - looking at that, he’s ignored those stats and I think he’s avoided all the controls…. @Barryscotland can you get a photo of the white connector so I can see what wires go into the bottom of which connection ..?

Right so looking at this pic he has a pair of wires heading into the Megaflo control panel (the lower one) and that should be wired as per page 19 of the installation manual. But from there, the wires marked 1-2-3 should go to the wiring centre and the zone valve controller for the cylinder as per wiring on page 19/20 of the manual If he has followed this correctly then the supplied zone valve (that has a micro switch in it) will trigger the boiler to fire when it’s needed using the live switched terminal 16. If the boiler needs a NV connection then it’s a bit more complicated but it’s all done with the valves. Tank temp / cutout is then driven by the correct thermostats on the tank ..! All of this is in the installation manual if he read it ….

Does your plumber have a G3 or equivalent ticket to install unvented cylinders ..? As that is very wrong advice ..!!! It is a mandatory requirement to interlock the control of the heat source to the thermostat on the tank. And the germs/legionella stuff is rubbish …

Who’s done the install as there has to be an interlock between heat source and the unvented cylinder as a couple of people have said to meet MIs and Building regs / warrants.