SimonD

I would just caveat this one with that a self builder is someone who turns the dream into a reality through their own best means, and does it independently. However they do it is up to them, but in IMHO turnkey, full design & build stuff doesn't quite cut it for me, even if the self-builder sources the land and does some of the preliminaries. I wanted to go down the route of having a contractor to do all the work but was so appalled by my experiences through the quote phase and through some intial building experience that I decided to do it all myself. During this time I've just had some labour help with family and friends to assist with heavy stuff, like installing <200kg windows etc. My wife insisted at one point that while I was away with my son, that I get in a chippy and a plasterer in. She didn't supervise them (as she didn't know what to look for and just paid them) and it was a tragedy, so they got fired and I had to re-do a load of their work. Other than the disaster above, the only people I've had in are the steel framing crew with crane for the steel frame. I've had an electrician in to start doing 1st fix but let him and his mate go as this was a mess too. I met a retired electrical engineer who then tought me the electrical side so I can do this all now myself and have a friendly electrician to sign of and install the EV charger. Heat and plumbing all completed by me. My sense of this is that sometimes I totally regret going down this route and sometimes I don't know how I would have felt if I didn't go down this route and how much debt I'd be in if I'd paid someone else to do it. The other side to this is that I've ended up training and getting certified as a heating engineer and have my own business doing this. So far I've got about 5 years doing gas systems and now I've gained a lot of experience, I'm moving across to heat pumps, probably exclusively in the near future. I'm still not finished either.......but feel like I'm in good company with @Russell griffiths as I'm 6 years in and actually not that far off, although next month I've told the family to leave me alone so I can swap out my gas boiler for a heatpump, so who knows. Now my wife has the common worry that she'll never feel warm with a 35C flow temp and need it hotter 😁

We had redwood (which is a pine) floorboards in a previous cottage. You often see whitewood, which is spruce, used too. Both are fine for flooring use. When we moved into the cottage they were either covered up with old carpet or an old flaky stain. We sanded them all back an varnished with a high quality varnish and they stood the test of time for over 12 years through 2 young boys too. They actually lasted better than an oak engineered floor we had in the living room. I'm a great fan of Bona floor products which are called a "Bona floor" in Sweden and are so easy to lay as you can re-coat in about 2 hours and have the floor complete within 1.5 days with 3 coats although it does take up to 7 days to fully cure so no covering with rugs etc. until then. We've also used varnish from Lakeland Paints which we were also happy with.

Yes, check this first. I don't work on enough Vaillants and their controls to know this off the top of my head, but the last time I saw a problem like this was the compensation curve set too low and the room stat/controller apparently still calling for heat but boiler only running at low flow temp so never reaching target - this was in the middle of winter with new house owners scratching their heads. A quick change to the curve and it all worked okay - but Vaillant controls are so dense and inaccessible, it doesn't help at all.

Yes, indeed. There is a company in our area who design systems so that when calling for dhw, there is flow not only the cylinder coil but also to a low loss header and straight back to return on the heatpump...who thought this was a good idea, I really don't know.

Generally, the design outdoor temperature for places between 51-52 degree north is -2 at 50m above sea level. If you're up higher and in a exposed location this would be slightly different, but -2 - -3 is absolutely fine for most of Wiltshire. Most domestic single phase EV chargers are 7kW I believe and any decent one will have load management to regulate charging according to whole house load, which our does very well. Calculations for this are a bit of a bogs dinner and highly inaccurate (e.g. using an industry standard method puts ours way over 100amps but is a load of nonsense). I would just ask an electrician to have a look and give you their opinion. If you have both EV charger and Heatpump you will need a DNO application anyway, whereas if it's just one, there are some conditions where notification is all that is required and some where application must be made.

I've just taken another look at this thread with a bit more focus and clearly seems that regardless of the Heamiser control issues, you have a fundamentally poorly designed and installed system. The heatmiser stuff really shouldn't have been installed and they should have installed the manufacturers controls with weather compensation. Next they shouldn't have installed a buffer as it's a dark art to balance the primary circuit (flow return loop from the heatpump) with the secondary loop (the side feeding the ufh and rads) across a buffer and you'll loose efficiency. At most you'd want a volumiser, preferrably (although some would disagree) on the return side. The the system should have been installed as an open loop without zoning. Depending on the rads installed (I've seen huge ones in nearly new build that are so oversized they allow the same flow temp as ufh) you could just run a set flow temp from the heatpump to your whole heating circuit. You can use trvs and something like and esbe mixer for small amounts of room control and different flow temps if absolutely necessary. Now you have a simple system that is far more efficient. Instead of investing more time in the heatmiser, I'd try to find a competent installer locally who can look at your system - I know you've had some in already, but asking any potential installer about their view on open-loop and buffers will tell you all you need to know about their knowledge.

Don't worry, you're not the only one. My fingers don't always have a great connection with the brain and sometimes my brain doesn't work to begin with 😁 Finally....... took them long enough to catch up, didn't it.

Class G 3 as of May 2025: (aa)the air source heat pump is not solely used for the purpose of cooling;

Intelligent go smarlty controls ev charging 24 hours a day but gives you a window of cheap rate leccy every night to use at your own pleasure - the window is actually slightly longer at night than with the dumb version go.

Yes, absolutely. And this will change a bit now with the r290 heatpumps working 'fairly' well up to 75C, so on an Octupus intelligent go rate, it becomes cheap as chips to batch charge on a reduced cop and then top up a few degrees with immersion. I think the cylinders should have a low level pocket for a thermostat so the call for heat to the heatpump is optimised according the stored temp around the coil. I've currently got a 200l thermal store knocking around and wondering how I can keep this in parallel to a heatpump unvented, potentially using the thermal store as a heat bank for the heatpump as we don't have a massive slab. But like with all these things, just got to get the calculator out and crunch the figures! + 1 I've been ordering from here for the past few months for all my installation jobs.

Yes

Yup, been there seen it and done it. I've lost a lot of hair in the process. I had a customer's house where the neostats would repeatedly pair fine up until the 10th stat and the last ones would refuse to pair, or would pair and then not work correctly. This was after replacing the wireless hub. I doubt it's the UH8, but more a tendency of the neoair stats. Why they can be problematic, I don't know. When you reset everything, did you proceed to repair from the closest stat to the furthest stat and do this methodically? It's worth calling Heatmiser tech support as they will help you through the process while to try to repair and get everything up and running again.

Heatmiser sell an opentherm mini hub that will control 2 zones with 240v relay to zone valve. The opentherm is done by output from the mini hub to boiler. So you could buy another neoair to replace the t6r and then wire up the minihub. The other alternative is to use EPH CP4 combination if you're not using a heatmiser wiring centre - with the cp4 you just have 2 stats with receivers with one receiver set up at the hub unit which is is wired to the boiler with opentherm. Oh, and especially if you're running a low temperature heating system (i.e. 55C or below), make sure the installer has actually installed the UFH with hydraulic separation, otherwise you'll probably end up with balancing problems between the radiator system and ufh. HTH

I've got a retired electrical engineer doing the 2nd fix electrics with me but passed me on to another guy to install an ev charger in our remote garage. Unfortunately, this one has disappeared into one of those trades black holes and just doesn't get back to me. I have a problem because I've got open trenches partly used for national grid to install my permanent supply, but also to take the cabling down to the garage. So, my plan is to just install this with the retired electrical engineer and then get it covered with the part p inspection. question is, what stuff do I need to install the infrastructure now and for the future? I'm putting in 25mm cable and the sparky who was supposed to do the job mentioned its useful to have a control cable, but I don't know what this is? Can someone here list everything I need from my meter tails to the ev charger, so I can get these trenches filled in and stop getting hassled by my wife about getting a proper charger instead of the wall plug? Thanks!

Yup, this drives me mental. I did an instal (natural gas) a while back where the owner was doing a deep refurbishment. I put in the boiler with modulating controls etc. and said she should call me when it's time for the ufh. However, the guy doing the floors, ripping them out and properly insulating them etc. never called me and did it himself with some other plumbing/heating muppet. Then winter came and the customer called me to say house wouldn't get hot. its a tiny cottage and they'd zoned it all up, then thrown away the brand new modulating controls for cheap shite relay ones and the system constantly short cycled. The circle completed with me tearing all their crap out and putting back modulation. Hey presto no short cycling. Makes my blood boil...

TBH the installers could have made their life easier by just using a heatmiser UH-8 as that can also control rad ch and dhw, and then no need for the abovementioned Navien wiring centre which I assume is just like the widely used Honeywell and Drayton standard wiring centres. It would also be a lot tidier I think.

Yes this. I'm really confused. The installation manual clearly shows switched live from wiring centre to boiler terminal 4 on CONM4. This is connected to the two orange switched lives that come from dhw and ch 2-ports, which is standard in the wiring centre. So to add ufh, there will be a switched live from the ufh 8 zone wiring Centre, which is sometimes volt free and just needs a bridge to com on the wiring Centre itself, and Bob's your uncle. Given the thread, this seems too simple. Or am I missing something? Some electricians too 😉 A customer of mine had new ufh installed while I was away last summer and then emailed me when i got back to say that neither the heating engineer nor his very competent electrician could get the ufh calling for heat to the boiler. It took 10 minutes 😁 I was tempted to say it was a very complicated and expensive call out but went easy on the electrician, who was there when I sorted it 😀

It could just be the fan. When you switch on ufh fan speed increases slightly to compensate for addition load.

Yes. Like the figures I posted earlier, this provides the best output. Radiator manufacturer figures are usually based on Top and Bottom Same End. But remember that rad output depends on the air temperature differential too. So for example with a flow temp of 70 with return of 50 you have a mean water temp (mwt) of 60. Mean water - air temp differential is then mwt - air temp so output differences between 21 degrees and 16 degrees are as follows: 60-21 = 39 60-16 = 44 To get the actual radiator output you then divide this by the manufactures delta, usually 50 so: 39/50=0.78 44/50=0.88 This means that with a room temp of 21 the radiator output is 78% of catalogue and with 16 degrees it's 88% Which clearly shows that even just 5 degrees has a big impact on output. You then take these results and multiply by the connector emissions factor which for TBOE is 1.05 or 0.96 for BOE Plus there are other factors used for the whole calculation.

Yes, but is it useful to believe its all down to delta T, even for general public and enthusiasts without also understanding the implications this has on heat output and mass flow rate and how this impacts the function of the system as a whole? By definition a lower delta T distributes less heat and therefore requires higher flow rates for the same output, some of which are impractical. And then with radiators heat transfer is based on Mean Water Temp to Air Temp differential as shown by the spreadsheet above so many radiator systems just won't work at low flow temperatures. Yep, maybe it's a sheesh post......😉

yes, they must be, but like most Heatgeek blogs, the nuance of all factors required to get a heating system working are missing, giving what I think is a misleadingly simplistic account, even if the principles are fairly simple. A lot of the figures above simply won't work very well with radiator systems without impractical modifications.

Sounds like the system needs purging which could also account for poor flow through some of the loops. Then a need to balance the loops. If this is a new/ish system is there a technical manual showing the theoretical flow rate through each loop? Setting them to this would be a great start.

Doesn't instill much confidence, does it? But yes, Opentherm is supported with the 050-W and 100-W which are plusbus, weather comp or opentherm, or relay. With the 200-W it's plusbus or canbus and you'd probably go weather comp. You can even add opentherm to many older 100-W with an X21 wiring harness for less than £10.

I can't speak for ATAG but you'd be far better off with a Viessmann 100-W or 200-W than a Worcester. 4 pipe out of the box PDHW with directly connected cylinder stat. then you just have to worry about heating control. They're also 12 year warranty out of the box if registered through the Viessmann installer portal. Too many fudges and system compromises (as well as unnecessary costs) doing it with a Worcester, whose system control implementation strategy is terrible IMHO. Edit: BTW poor system control, heating not working very well in new and newish builds with Worcesters installed with UVC and combined rads/ufh is one of my common jobs to sort out!

What we're you using for Opentherm control? This is entirely possible within the protocol - the master simply asks for relevant flow temp from boiler when the dhw cylinder calls for heat and you wire in a relay for any external valves.