ProDave

Fadebec too expensive and too tall. Joule too expensive and the crafty so and so's don't even include the installation kit which is extra. It's going to be a Telford, which apart from anything else seems to be the shortest 300L cylinder I have found and the cheapest (though I still think it is a LOT of money for what it is)

Just wanting to make sure it's not going to try and extract heat faster than my low powered heat pump can deliver and cause some issue. I want to run it by the technical help at Telford first.

Interesting. When we ordered ours a few years ago the only options were painted inside.

@jack As someone with a near identical setup. If you set the HP hot water temperature to (say for example) 50 degrees. How hot will the water in the tank actually get? I suspect the issue is as you get close to the HP temperature the rise in temp of the HW becomes very slow and that might be where the bigger coil wins in getting the HW those last few degrees?

Okay, technical question. What are the advantages AND disadvantages of the larger heat input coil? It is all about heat transfer and heat up times. Bigger coil = faster heat up time? BUT only if the heat pump can keep up with what the input coil can handle. My heat pump is only 5KW It's a low energy house with the max heating demand at -10 outside and 20 inside a little over 2KW so we only need a small heat pump. So on the face of it the 3.3m2 coil might be the right one. I am questioning if there is any merit in the larger one if the limiting factor may end up being the power of the heat pump? And does the low power heat pump even mean the much cheaper standard input coil might be okay? I can't seem to find any technical info on the "power" ratings of the various coils, and Telford have shut up shop early being a Friday so I can't speak to them until Monday. Not much from other suppliers. Jewson want £926 for the Telford, and TP have offered a Gedhill for £900

You seem to be prepared to give up the 20% VAT saving on the garage, because you can't afford it up front. This seems to be a classic case of borrow the money for the garage? as long as the interest does not exceed a total of 20% you are onto a winner. How long would this shortfall be and how much? thinking 0% credit card (usually about 3% fee) and roll it over to another if you have to.

Our building warrant took a few months to finalise. There was some rework of drawings needed and some re sumbission. It seemed every month BC sen a list of outstanding points waiting to be addresses. An the whole they are a lot more approachable than planning and much more flexible to work with you to get everything agreed. And there were no extra charges for alterations during the process.

indirect+solar seem to have a similar premium. Off to phone TP and Jewson for a laugh. TP don't do Telford so it will be interesting to see what they quote

Just glue and screw a wooden back board to the wall. I would ditch the pocket idea. You just know it's going to leak which means you have to tank the pocket before you tile it.

So standard tank 2.3m2 and heat pump tank 3m2 input coil. I don't see the significance ot tapping heights. All I want is cold water in at the bottom and hot water out at the top. No hot water return or anything fancy. Would the performance with a heat pump really be that much worse with a standard input coil? If so in what way? slower heat up time? or hot water would not reach heat pump temperature meaning heat pump has to run at a higher temp, or more immersion boost needed to get from heat pump temp to final temp? I would expect there to be a difference in price, but not almost 50% extra for the heat pump version. @Nickfromwales please do make that phone call and let me know what you find out.

The Telford cylinder does not use a heat exchange. I only want 1 heat input coil but for a heat pump they specify a larger area input coil, presumably to get better conduction so the cylinder temperature will get close to the input temperature, but it seems to be adding £250 to the cost which seems rather a lot. I have had a reply from my tub, they are "checking" if this cylinder really fits the description given. So Telford claim the HP version of the cylinder has a 3m2 input coil, What I can't find anywhere is the surface area of the standard input coil. i.e. how much difference does it make?

Trying to source my hot water tank. Usual parameter - cheapest possible. Requirements Unvented 300L capacity, separate expansion vessel (not built in due to limited height) Input coil suitable for a heat pump. 1 immersion heater In addition to the standard tank thermostat I need a separate thermostat pocket as the heat pump has it's own sensor. Cylinders 2 go are quoting £898 inc VAT and delivery I am told the Telford part number is TSMI300/HP When I search for that, this comes up https://www.mytub.co.uk/tempest-unvented-cylinder-indirect-300l-tsmi300-product-740532 Now that does not have the /hp on the end of the part number, but it talks about "Our standard Heat Pump coil has a surface area of 3.3m2, as a result the smallest tank we can offer is a 200litre. Smaller capacity cylinders are available where a lower surface area coil can be used." So it seems to imply it is the heat pump version. What does the panel think? Assuming that is a "mistake" it seems there is a premium of about £250 extra for having the heat pump input coil, that sounds rather a lot.

Okay so it's English building regs and whatever the local vernacular is which may well mean 2 storey is okay.

Our first house was built (to a bare shell) on a fixed price contract. Every time there was a small change the builder sent a "notice of variation" immediately so we knew the extra costs coming. This time round I entered an open ended contract with the builder. We were having trouble selling the old house, so my instructions were basically "carry on until I say stop" and that point happened when the frame was built and the roof was on (but not tiled) and I have carried on alone since then except for rendering and plastering. I did get the same builders to supply and fit the windows later on. We parted on good terms with them fully understanding it was simply a matter of no money in the pot to pay them for any more work.

In my case I did the planning drawings, then paid an architectural engineer and a SE to detail the design, The exorbitant architect fees I referred to was for the previous house, where the two architects wanted to base their fees on a high percentage of the estimated build cost one quoted £25K the other £30K and neither would negotiate. To make matters worse both estimates of the build cost were roughly twice what it actually cost. Had they offered a reasonable fee as in this example I would have used them,. In the end in that case I paid £2K to the timber frame company for all the drawings.

You first do a design SAP for building control approval. At the end that is updated with an "as built" SAP for BC sign off to take account of any changes that might have happened. If I had been quoted those sorts of figures from an architect, I would have bitten their hand off. Some think I don't like architects, that is not true. What I dislike is when I last tried, they wanted to charge me roughly 6 times what you have been quoted for the same scope of work, and they would not even negotiate the fees a little bit, let alone bring them down to the reasonable fee you have been quoted.

When I did the sums based on the design SAP my RHI payment would total £2030 over 7 years. It would actually be lower than that if it was based on the as built SAP as that will be better due to an error on the design SAP that had my roof insulation wrong so a poorer U value for the roof. I concluded it is not worth the bother of claiming the RHI. I am DIY fitting my self sourced heat pump. To get an MCS installer to supply and fit one would add more cost than I would be able to claim. You say you would get £8400 but you would like to make your house worse so you can claim £10,500 You know that would leave you with a poor house with a high running cost long after the 7 year RHI payments have ended? Why would you want to do that?

That reminds me of the argument my BIL had many years ago. He drove into his local tip and proceeded to drag the 1 ton builders bag of garden waste out of the back of his pick up truck and start emptying it into the skip. At this point the manager came storming over saying he can't tip that here. The argument hinged on the sign saying "garden waste, 1 car, 1 bag" and my BIL:'s insistence that he indeed only had 1 bag. The argument ended when my BIL said I can either empty the contents into the skip, or I will just drive off and leave it on the ground (it was out of the truck by this time) I don't think they hand ANPR cameras then but I suspect he was unwelcome after that. It is absurd that they make it difficult for people to dispose of their waste responsibly. And then they wonder why there is so much fly tipping that will cost them more to clean up than if they just let people take it to the tip. It annoys me as it's my council tax money they are wasting with policies like that. It also makes me feel even more, the "bottom of a wheelie bin" is a damned good place for all sorts of stuff to go.

I am convinced some future owner is going to rip this lot apart (when they knock it down to rebuild) and wonder at the sheer number of Fosters cans left behind build into the walls.

^^ probably a bit late to say this, but the bottom end of your ply is floating. That will flex. I would have put a dwang (noggin) across there t catch the end of the ply and screwed it to that. Then you only have a ply and plasterboard deep gap to fill and it will be one whole lot more solid.

Okay, if this is West coast of Scotland, you won't be allowed 2 storey. 1 3/4 at most, i.e. rooms at least partially in the roof. A 200 square metre footprint on a 750 square metre plot sounds too big, especially when you talk of a detached garage etc. I hope you have mains drainage available otherwise you are going to struggle. Utility and storage is way too thin. The kitchen / diner is too thin as well for its width. If the front faces West, and has the view, then I would make half of that the kitchen (with dining facing the back / east) and then you can have a nice big living room triple aspect east, south and west making the most of the sun and the views. Your location would help then we know which building regs and which local vernacular to follow and a plot layout with respect to neighbours as well etc.

The dump valve needs to open when the thermal store is getting too hot. In this scenario it needs to do it when there is no mains power so a motorised valve is out. It needs something like a capillary operated valve that opens at a set temperature with no electricity. Does such a thing even exist?

As you say, horse's for courses. I don't want to routinely be storing water at 75 degrees. The heat pump won't get it that hot, so it's the immersion heater to get it the final bit. So I want to store it at a lower temperature. I will bu using a TMV on the output to deliver HW at the lowest temperature that the thermal mixer showers will cope with, so on the days when the sun shines and the HW in the tank is a lot higher, you will still get the same temperature water, but on the days when there is no significant PV generation and you have to buy the electricity for the final heat up, it will only heat it to the bare minimum temperature.

But what IS it? There is not enough detail. Looks to me like a plastic thermal store tank.

I am designing a system that will heat water when it is most efficient to do so, not all the time on demand. So I am not trying to "keep up" with demand and hope the boiler can cope, rather trying to work out the best way to store a certain amount of hot water to be used with probably no heat input during usage. Heat an UVC to 60 degrees and tun the hot tap, you will get water out at 60 degrees with very little drop in temperature until it suddenly goes cold at the end (note no heat input during this time) Do the same with a thermal store, and the temperature will gradually fall as you are extracting heat from a static volume of storage medium So to maintain say 50 degrees HW flow for a set period with no heat input will either require a larger TS than UVC or for the stored temperature to be higher.