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I still find it incredible that I spent so much money on a complete lie. This is from a shop specialising in Veissman kit:

Spotted something a little odd on my energy bill this month: “You’re on our cheapest gas tariff of its kind. You could save £114.22 a year by switching to Loyal Octopus 12M Fixed.” I’m not sure in what world these two sentences do not contradict each other, but it has reminded me that a couple of months ago I posted on this forum to ask if I should fix my energy rates and somebody said wait. Can’t remember if it was @ProDave or @Mr Punter or somebody else, but just wondered what forum users are doing in terms of tarifs, fixing etc. I’m keen to stay with Octopus so don’t mind paying a small premium for that, but still need to reduce bills as much as possible (and yes, for those that have kept up with my other thread, I’m getting my Veissman system upgraded…).

If that includes balancing and commissioning, and they are confident of not damaging your plaster work when they put the vent terminals in, that’s a pretty good price, at least for London. Which terminals are you going for? I’ve got cheap ones in my bathroom and kids bedrooms, expensive lindab airy ones elsewhere. Quite a big difference in audibility. Would recommend plumping for lindab airy if you can.

Thanks. What is high flow temp ufh? I installed slightly thicker ufh pipes (I think they are 15mm diameter) at 150mm distance from each other. Is that high flow?

Thanks @Lofty718. Following your and @SimonD’s recommendations I’ve reached out to an engineer that specialises in Veissman. Had a chat with him this morning and his preliminary view was that weather compensation and covering to a 4 pipe system would be worthwhile as it would save me money, significantly more than the cost of the upgrade. The only thing that he said against weather compensation was that it would only not be of benefit in a house that only needs heating for a couple of hours in the evening and a couple of hours in the morning. In those circumstances, he said an on/off system MIGHT make sense. He emphasised that he would still err on the side of weather compensation, but I do find this interesting given four days a week the house is empty from 830 to 5ish and we don’t run the heating at all between 10pm and 5am. Maybe that’s enough is to justify weather compensation though. I am slowly coming around to the idea of removing all/most zoning, and converting to weather compensation. Still hampered by my own ignorance. I think what’s still holding me back is: 1) what is load compensation ? 2) I need to understand this further: particularly in light of the two matters below: First, we have a daily situation where it makes sense to have very different temps in different rooms: our master bedroom, has slightly more heat loss than our other bedrooms, because it is more exposed/has greater surface area ratio of external walls to volume of room storage. We like this about the master bedroom, because it keeps it nice and cool at night, usually around 18C. We would only turn the heating on if it falls below 17.8C and that only happens in very cold winter weather that lasts for more than a day or two. You mention balancing allows different temperatures in different rooms, so presumably I could still keep this room really cool because it’s on a separate loop. Second, about once or twice a week in winter we run a wood burning stove. How would we switch off the heating in the rooms that benefit from the stove without zoning and thermostats?

Any idea how I find that info? Playing around in the display, I found readings for burner modulation, flow temp and flue gas temp, but not return temp.

Right next to each other. Here is a as photo, boiler on the right, LLH is the anthracite polystyrene clad box immediately to the left of the magma clean, which is immediately to the left of the boiler.

I presume you mean at the boiler, rather than at each of our four UFH manifolds?

Re the comments on weather or compensation rather than room stats, I’ve mentioned this elsewhere on this forum, but I don’t see how that is meant to work in a house which has some rooms which are east facing, other rooms which are west facing and one fairly large room which is neither. Solar gain, even in winter means that our east facing room is warmer in the morning and cooler in the evening than the west facing room. Yet each of two rooms on opposite sides of the house is used as a bedroom for each of our kids. They don’t have the same temperatures without heating on, and we require heating at slightly different times because they have different schedules. So having each room on its own zone with its own stat and timer is very helpful. Similar issues at play in respect of many other rooms in the house. Each room, without heating has its own micro climate - apart from the different orientations, the house is a mixture of constructions, with some of it built in the 1930s and upgraded now, and some of it built from scratch now. The house is on three floors to make matters slightly more complex too. I’m not sure how one could retain the control we have now, without individual room stats and timers in each room. Maybe the answer is load compensation, I’m not sure what that is???

That’s helps put things in perspective. Thanks! Reflecting on all this, I know my situation isn’t terrible, because I imagine we use a fair bit of hot water and we like the house fairly warm, yet our bills aren’t crazy. But it remains rather disappointing because I suspect that if I’d have everything done properly, I’d be saving something on my bills, but the question is what? I did look into a professional design, but it was quite expensive, circa £2k, and the two companies I spoke to seemed to be wedded to the idea that I should get a Veissman storage combi boiler which didn’t sound right for our usage case and in circumstances where we had space for a 300L cylinder in the loft. So I thought I would just do as much research myself and then specify the model of the boiler I wanted, and the size of the cylinder and the heating zones, and that I’d leave the detail of how to set that up to the professional. I can’t now remember how the low loss header came into the equation. I think it was an alternative to buffer tanks as (a) I wasn’t sure we had space for a buffer tank; and (b) the installer didn’t think a buffer tank was necessary, but I was worried about short cycling. I am not really sure how I feel about raising this with the installer. I could make an argument that he was incompetent in that he did not install according to best practice, but I never told him I wanted a specific set up. I just assumed he would install it in accordance with best practice. On the other hand, the following analogy appears apt: When I get in a black cab in London (as opposed to a clueless Uber) and I give the cabbie an address, I expect him to take a reasonable route. If he doesn’t know the route, I expect him to ask or to look it up in an authoritative source. Within my fare, I’m paying for the petrol consumed as well as for the cabbie’s time, and so I’m entitled to get a reasonable route that is reasonably quick and reasonably petrol efficient. Am I not entitled to the same in respect of my boiler and UWC install? In that case, whether it’s his fault or mine, probably comes down to how inefficient the system is compared to a 4 pipe system. If significantly less efficient, then it’s probably not a “reasonable” install. But if it’s costing me no more than £75 extra a year in gas, it’s probably not terrible.

Far. Boiler is in utility room on ground floor. Tank is in the converted loft on second floor (although pretty much directly above it, so maybe 6m away.

Sorry Marshian, I’m not understanding your response. I (now) understand that PDHW is best design, but in the absence of this I’m trying to understand how much worse of my current setup is, given I had understood there were efficiency benefits of using a low loss header.

To at to my previous post, my understanding is that for a boiler to go into “condensing mode” the return temperature should not be higher than about 55C and a low loss header can assist with this. So I’m just trying to figure out if the benefit I’m getting from the low loss header might be cancelling out the efficiency deficit of not having PDHW.

@SimonD thanks. Please could you explain what is wrong with my current setup and how much more efficient heating the cylinder would be if I did this work? Just trying to understand the cost benefit analysis.

From what I can see, it’s two pipes, plus a gas pipe: I also have a low loss header, not sure if that impacts your views (see next post)

But the HW control is separate to the UFh controls. And whereas the UFh controls are zoned and use low temp water, the HW control doesn’t. So if you could recommend a smart controller for the Hw I’d be grateful.

If this is accurate, then this marketing piece is one of the most misleading adverts I’ve ever fallen for. Shame we don’t live in Australia or the US otherwise this would be a great class action.

Other question I have is whether load compensation is that relevant for a house that is only heated by UFH? The boiler sends hw to the manifolds and its mixed there. There are very rarely higher deltas between desired room temp and actual room temp of 2C, 2.5C at most.

Are you sure about this? I wasn’t aware. If it’s true, that’s pretty cheeky of Tado. I kind of assumed that smart meant smarter than a bog standard controller. I’m not going to change the UFH tado thermostats, but if you think there is a benefit to changing the HW controller, I’m happy to consider it. Is there something that can be controlled away from the house that also meets the requirements you mention?

I got it from the Tado store. There isn’t much data on its exact specs online, but with all the cable ports it comes with (see second picture, here) I would be surprised if it’s missing much functionality.

You can control it from your phone, regardless of where you are. We use that feature a lot. It also does geolocation so that the heating on can be overridden to off when you are away. You can set a radius so when you are within a certain distance of your house it will turn back on. Other smart feature is lots of data gathering in terms of humidity and temperature graphs. There is also an open window/door detection feature which works well in an airtight house. If it senses a draft at the same time as the heating is on it will tell you and ask you if you want to turn the heating off in the relevant zone. Finally, and this is the only feature that requires a subscription, it can do weather compensation for you, if you pay a £3 monthly fee. We don’t bother with this, though would have been helpful for when the temperature suddenly drops. I might sign up for a couple of months to try this feature out.

Thanks everyone for the feedback. It seems I should have just accepted my installer’s recommendation to leave it running all the time. Seems so counterintuitive, but I guess that’s what our boiling water tap does in our kitchen (re boils for 20 sec every 20 min to let the water at a constant 98C). So if the theory works for that, then maybe it will work for a cylinder that is 60 times bigger as well. I have now reset my HW timer to do the below schedule, and will drop the thermostat by a couple of degrees. Final query is whether to have it running 24/7 as opposed to only when we are awake. Noise isn’t an issue.

I’m not really sure the answer to this. I didn’t realise boiler setups were that complicated. My boiler and heating system and tank was installed by an electrician and a gas engineer. I d did some research and came to a few conclusions like: 1) Veissman together with a Veissman low loss header would prevent the need for a buffer tank and would not short cycle. 2) 300L cylinder should just about meet our needs 3) PIR activated secondary loop would be beneficial. 4) I like tado. 5) different pipe diameters for different applications, eg 22mm for bath, 15mm for shower, 10mm for basins. So to the extent there was any design, that was it. I conveyed that info to the gas engineer/plumber, asked him if he was Veissman registered, he said he could get approved and registered. A couple of months later he showed me the Veissman certificate for his registration, and after that I let him get on and do the work. My electrician asked me how I wanted to control my heating and HW and I said tado and he did the rest, choosing which wiring systems etc.. It all works, and my bills have been pretty low considering it’s a 5 bed house with fairly high HW use and probably would only score a C, maybe a B, on a EPC. I have a tado controller wired to the boiler, and that tells the boiler to heat the cylinder, save that it is overridden by the cylinder’s stat when the cylinder stat decides it’s reached temp. With retrospect, I should have got the system properly designed, as then proper insulation for the secondary return/loop pipe would have been specified, and we might have a more sophisticated HW heating system but given everything is working well, I’m not sure how much I would have saved in the long wrong by paying for a professional design.

Instinctively, it just seems like a very inefficient use of gas. Even if I’m wrong about that (am I wrong?), is it not going to increase the wear and tear of the boiler?