SimonD

Interesting publication about the effects of retrofit insulation, which, as ever, points towards a mix of interventions as well as behaviour. https://www.cam.ac.uk/research/news/insulation-only-provides-short-term-reduction-in-household-gas-consumption-study-of-uk-housing

Yes I'm aware of tado and aware of the reversal in decision to bring it back, even if messily. Every other controller I install has a clear ERP label that tells me what I'm installing. The Honeywell T6 is ERP class V which is a modulating control using opentherm. Ideal Halo products are class VI, again modulating using opentherm. I'm interested to hear who else you're claiming has degraded opentherm to on/off?

This is simply not correct. In my experience, it's often not the controllers that are at fault, it's how they are installed. When choosing a controller it's important to check the ERP rating of the controller as the combined controller and boiler ratings give the overall ERP of the boiler installation according to Part L. Below is a good explanation of the ERP classes taken from https://phpionline.co.uk/feature-articles/erp-control-classes/. Class I On/off Room Thermostat: A room thermostat that controls the on/off operation of a heater. Performance parameters, including switching differential and room temperature control accuracy are determined by the thermostat’s mechanical construction. Package/system space heating uplift = 1% Class II Weather compensator control, for use with modulating heaters: A heater flow temperature control that varies the set point of the flow temperature of water leaving the heater dependent upon prevailing outside temperature and selected weather compensation curve. Control is achieved by modulating the output of the heater. Package/system space heating uplift = 2% Class III Weather compensator control, for use with on/off output heaters: A heater flow temperature control that varies the set point of the flow temperature of water leaving the heater dependent upon prevailing outside temperature and selected weather compensation curve. Heater flow temperature is varied by controlling the on/off operation of the heater. Package/system space heating uplift = 1.5% Class IV TPI room thermostat, for use with on/off output heaters: An electronic room thermostat that controls both thermostat cycle rate and in-cycle on/off ratio of the heater proportional to room temperature. TPI control strategy reduces mean water temperature, improves room temperature control accuracy and enhances system efficiency. Package/system space heating uplift = 2% Class V Modulating room thermostat, for use with modulating heaters: An electronic room thermostat that varies the flow temperature of the water leaving the heater dependent upon measured room temperature deviation from room thermostat set point. Control is achieved by modulating the output of the heater. Package/system space heating uplift = 3% Class VI Weather compensator and room sensor, for use with modulating heaters: A heater flow temperature control that varies the flow temperature of water leaving the heater dependent upon prevailing outside temperature and selected weather compensation curve. A room temperature sensor monitors room temperature and adjusts the compensation curve parallel displacement to improve room comfort. Control is achieved by modulating the output of the heater. Package/system space heating uplift = 4% Class VII Weather compensator and room sensor, for use with on/off output heaters: A heater flow temperature control that varies the flow temperature of water leaving the heater dependent upon prevailing outside temperature and adjusts the compensation curve parallel displacement to improve room comfort. Heater flow temperature is varied by controlling the on/off operation of the heater. Package/system space heating uplift = 3.5% Class VIII Multi-sensor room temperature control, for use with modulating heaters: An electronic control, equipped with three or more room sensors that varies the flow temperature of the water leaving the heater dependent upon the aggregated measured room temperature deviation from room sensor set points. Control is achieved by modulating the output of the heater. Package/system space heating uplift = 5%

I lean towards the Vogue Max as my preference but have done a few Logic Max installs now too. I've installed some T6Rs with heat & hot water so if these have the same wiring as the earlier T6, then is fairly straight forwards. In the receiver box, wire up your heating to opentherm on the boiler (bridging the SL1 connection) and then wire the hot water switched live to SL2 on the boiler via the junction box, cylinder stat and motorized valves. I prefer using 2-port diverter valves, so have a normally closed on the dhw side and normally open on the ch side that is wired to the normally closed valves switched live so that it closes when the dhw diverter opens. Intergas are good boilers but if you look at the minimum output on modulation the Ideal is slightly better, except for the 40kW intergas system boiler. By this I'm assuming you're intending to have everything on constantly and rely entirely on the flow temperature set point to manage room temperatures? The T6 controller will provide you with some additional control, especially if you don't want your heating on all the time. I also wonder whether this setup provides less overall control of the system than load compensation using programmers/room stat/ and opentherm. Ideal's own installation manual gives an ERP of 2% with weather comp on its own and 4% used in combination with a programmer.

I think Part L has been done really badly. There is a separate section with the AD that details what needs to be done for boiler only replacements. I've seen there's also confusion about what impact Part L has on boiler servicing requirements. I'm completing my Part L energy efficiency and low temperature system design soon for MCS registration so I wonder whether this training will help to decipher more of the code!

My experience is so far is mixed. With the new Part L we're technically only required to design to 55C flow temps where there is a new heating system installation. When it comes to replacing a boiler, it's about ensuring that the new one doesn't perform any worse than the one you're replacing and then that controls are installed that provide either weather/load compensation, or automisation/optomisation, or flue gas heat recovery. There is also a requirement that if you install a new boiler you should also install trvs if there aren't any. The part that does get a bit messy is where you rightly point out that in order to make the system efficient, you ideally need different dhw and ch flow temps. In my experience in many instances it's the boiler rather than the controller that causes the problem, simply because it cannot deal with this difference - it beggars belief the number of installers around me chucking in a certain model Worcester Bosch boiler despite this problem, for example. However, you can find the ones that do, even if the manufacturers might not explicitly tell you about this. I've personally gravitated towards Ideal boilers because they have a separate switched live for dhw that gives a flow temp of up to 80C and a normal switched live that can be set to 55C or lower for CH. Even better, I can install an opentherm controller to the boiler to modulate the ch but still use the 80C sl2 for hot water (it's also possible on some models to set a max boiler water temp to bring down the dhw to whatever you like, if you want). What I've been doing with system and heat only installations is reconfiguring to PDHW using a combination of normally open and normally closed diverter valves that make this system work properly, even in multi-zone installations - basically the normally open valve is used on the ch side and normally closed on dhw and when the cylinder stat calls for dhw heat, it opens the normally closed at the same to as closing the normally open. For controllers I've been using either the Ideal own systems (Ideal Heat & System Halo does support priority hot water, which is good) or Honeywell, but have done and will be doing installs using Nest/Hive/Tado, usually specifically down to customer specifically asking for them. With Tado, I'm still very unhappy with how they've dealt with Opentherm here in the Uk and when I explained what was needed now - a wired unit + wireless extension, a recent customer wasn't too happy either, asking me if I couldn't just get an EU version for them.... Problem is that most customers have no idea how each individual controller works and it's difficult even as an installer to know these things properly. More widely it's a total mess, a lot of installers are ignoring these new controller requirements so they're quite happy to bung in a new boiler and wire it up to existing controls and don't seem to know about modulation. I suspect it's the same for new whole system installations where it'll be rule of thumb. From a customer perspective, feedback has been quite interesting. Only very recently are they asking about flow temperatures and how to best set them up, so the message is starting to get out there. I've just read this. I understand the rationale behind the idea but I think they've missed a number of critical elements and is a bit misleading. For example, you won't get a replacement boiler in just 2-3 days as there's a serious shortage of installers across the whole country, and according to recent industry research only about 1/3 of existing gas engineers are planning to train to do heatpumps, leaving us in a very dire situation for resources. Yes, the boilers are most often distress decisions, but I don't think the library idea necessarily works. If a customer is going to be asked to pay £1500 for the installation of a new boiler that is expected to last for 10 years, it's a bit steep to ask them to front this cost for a leased boiler, for potentially a year or so, something that will impact poorer purchasers much more. I also think they've got to reconsider the reality of making the home heatpump ready. In many instances I think it'll take a good 10 years for this to happen and by then they're better off just purchasing a replacement boiler (from a convenience, cost and function perspective). The one thing that doesn't get much air time, but has been making the rounds much more in the industry press is the hybrid heatpump/boiler, contained within a casing about the same size as your typical boiler. As a transitional idea, this is making more and more sense to me, simply because of the problems we've got with our housing stock and existing boiler install base of combis. It would also help in respect of making the boiler much better at modulating output through the year.

In this instance I believe that the flowchart is referring to the room thermostat set point rather than the flow temperature set point. Ideally you want to see the programmer/boiler modulating before this set point is reached. (Interestingly on my Honeywell Evohome setup it tells me the percentage modulation compared to the boiler flow set point, which as you say will vary according to how close the room is to its set point and weather conditions) It seems, however, that the flow chart is a troubleshooting one that looks at diagnosing problems with modulating or cycling of the boiler due to flow rate issues within the heating system? I've seen this recently where low flow rate causes a too high flow/return temp differential (e.g. more than 38C and thus eventually throws a fault at the boiler), or that flow temp rises too fast so the boiler has to switch off (flow temp rises above the flow temp set point and too quickly), again due to low flow rates. With the new building regs I reckon there's going to be far more head scratching going on with Delta T/Flow Rates/Modulation/Cycling - in the real world it's turning out to be a time consuming process to get right! I'm finding quite a few issues setting all this up with new boiler installations on existing heating systems. Does your boiler have a flow rate sensor and a way you can access this information? Then put in a phone call to Glow worm customer technical support and see if they can give you specific flow rate figures to work by (Sometimes they don't like giving out too much info mind you). Alternatively, there's a straightforward calc given by Grundfos: https://www.grundfos.com/sg/learn/research-and-insights/calculation-of-flow. Or there's the CIBSE Domestic Heating Design Guide that has a more detailed section on flow rates: https://www.cibse.org/knowledge-research/knowledge-portal/domestic-heating-design-guide-2021

I think you might be better off measuring up the gear and then ordering a replacement spur gear with pin holes from a bearing supplier or other industrial supplier. That way you'll most likely get the right diameter and maybe a better quality gear. You'll need to know the module: http://www.metrication.com/engineering/gears.html

Yup, I bought a load of gun grade airtightness foam, well only a pack of 6 thankfully, from a 'full priced' reputable online merchant only to find out the foam was to be out of date the week I purchased and received the stuff - I didn't check the cannisters until a few weeks later when I used them. I don't know how much we need to care about the use by date on these products but the foam wasn't ever quite right. With these products I now use suppliers who specialise in this stuff as I suspect they have the trade volume. Who knows?

The proper way is to have adhesive mortar and mechanical fixings. The mortar obviously has a role as an adhesive but it also evens out the substrate. The mortar also prevents convective air movement behind the ewi which can have a significant impact on performance. Depending on the brand the adhesive can be applied in a continuous cover, or as thicker beads around the back perimeter of the boards with some dollops in the centre. Question is whether if the builder didn't know this, is he up to the job? EWI detailing is important, round all the penetrations and at eaves and dpc level. Has this been designed, discussed and agreed? Do you have drawings or anything confirming the detailing?

I would tell them that you're going to put in a call to Gas Safe and ask an inspector to come out and have a look.

My first question is why not get a replacement casing? Has the person condeming the boiler checked availability and pricing as an option? On most boilers nowadays (at least 15-20 years) the casing is classed as part of the flue system and if there's a hole it means the boiler ain't room sealed any more, thus dangerous. I think there's generally some confusion about boilers types and systems here. Perhaps it's easier to think of the boiler as just the heat source and then separate the systems that use the heat. One system is the central heating, the other is domestic hot water and with domestic hot water there are two sides to the system - the heat input and the heat output. Both system and heat only boilers heat a defined body of water contained within a set of pipes that provide the heat input to the radiators and hot water cylinder. This heat input circuit can either be open vented or sealed. A heat only boiler is usually found on an open-vented system, but, using an external expansion vessel, can be sealed under some circumstances if deemed okay by the manufacturer. A system boiler is sealed as the system boiler has a built in expansion chamber. This circuit of water is, through diverter valves pump through either the hot water cylinder or the heat circuit, or both. The difference between the boiler types is due to what is included in the boiler and as correctly pointed out above a system boiler has pump and expansion valve, some have the automatic bypass fitted and so forth, so there's less additional stuff needed. With heat only you need to install a pump and bypass etc. separately. You then have the heat output of the hot water cylinder. On either of these boilers, there can be an unvented cylinder, which simply refers to the fact that the hot water is stored within the cylinder under mains pressure and is not vented to a F & E tank in the loft. This has no effect on the heating circuit of the boiler as it's kept entirely separate by using an 'indirect' cylinder. So overall, either/both the systems can be open-vented or unvented so it's important to differentiate between which particular side of the system is being referred to. Not necessarily. The external mains upgrade is required for the unvented cylinder to work as designed. You could actually install a system boiler and just remove the heating F & E and at the same time retain the gravity fed open vented hot water cylinder until you have the work done. Your minor risk with this is that the pressure within the heating system of the new system boiler might cause leaks in the old system - but I think that risk is probably fairly minor.

No I can't. The wired version is not the one I'm after, nor is it the one my customers are after. Why? Because so many existing wired thermostats are installed in really stupid places in the UK. I'm just doing an install in a Georgian townhouse. The thermostat is installed in the basement next to the hot water cylinder and existing boiler, a floor mounted old behemoth of a boiler. I just completed another installation in another Georgian town house where the wired thermostat was in the 1st floor landing. I did 2 services in newbuilds where the wired thermostats had been installed in the hallway only an couple of meters from the front door with no relation to the living spaces. The customers don't want to pay for rewiring of a thermostat to somewhere else. So Tado still doesn't do a wireless smart thermostat that does modulation unless you have a combi. Still a problem in my view. At the end of the day, this is the biggest problem - to educate the installer base to do a proper job. But then it doesn't just apply to Tado. I just fixed a Vaillant system where the previous installer had fitted two Vaillant controllers to try and get it working and the problem was merely the heat curve.... but I have to say that in both instances as also with the Honeywell Evohome the manuals are total and under crap - if the manufacturers took the time to produce proper information, the story might just be a tiny bit different. IMHO

I really liked my Festool HK85. It was a beast until I experienced the so called 3 year service included service from Festool. My experience from this was that they do the absolute minimum they can. My HK85 went back twice and the second time I was getting some pretty bad noises and vibration from the saw within a few weeks of receiving it back from them the first time. The second time it came back supposedly fixed but with smaller noises and vibration and very much not right - the cutting blade vibrates slight against the saw body when you start it up but apparently this is fine by them. Funnly enough, if you send the same product back after the 3 year service has expired they'll charge you for making the saw like new. After this experience, I won't be buying Festool again. I've found my Mafell to be very robust and if I was going to buy a cheaper saw I'd probably opt for the Bosch GKT 55 as it is essentially a Mafell with some differences.

Only on the combi model it appears. As for that video, it smacks of the type of company that makes my blood boil - removing functionality from a product without telling anybody in the market you're doing that? I personally only found out just before it was too late that they'd done this and no thanks to the company! It also suggests they have little clue about the market they're dealing with here in the UK. If there's not much uptake of a product, would you not sensibly investigate why and try to resolve the problem rather than dumb down the product to make it cheaper and at the same time claim the reduction in heating costs probably only realised by modulation? Also, there doesn't seem to be any understanding that they might need to communicate better to both customers and professionals doing the installation to understand the benefits of modulation. To me that video does very little to build any trust in the company even if the technology is fundamentally well designed - it still doesn't appear properly support modulation on all heating systems and boilers in the UK, and they haven't moved beyond Y and S plan.... IME lukewarm radiators are not the problem, it's being cold in the house.

I have those tracks too, mostly used with the Festool HK85 rather than the TS plunge version. I have the Mafell plunge saw which uses both the Festool tracks and the Mafell tracks. After 4 years of use I found the Festool tracks to be really robust apart from the splinter guard which always peels off. The biggest issue is aligning them even with the self-aligning connectors I bought. Always have to check with a straight edge, especially for 2nd fix and making cupboards/cabinets and then if you knock them while moving about...... Overall I'd have to say I prefer the Mafell track system, which I think Bosch also uses.

Definitely not in the UK as Tado has removed Opentherm support in their UK models - now that is rubbish, what about working with all the UK boilers that are Opentherm compatible? It's interesting to hear wider experiences of EvoHome. I have a multi-zone setup using Opentherm and priority hot water and it works very well. In the early days I received a communication error that Honeywell support attributed to me having set the system up on a way they said shouldn't be possible and had a bit of a laugh about it - I did have it set up in a peculiar way at that time (partly because I like to play around with these things to see what works and what doesn't). When I spoke to their support they acknowledged the EvoHome setup isn't the most accessible and suggested the best way is to attend the training days they provide. The more I use the Honeywell Evohome the more I appreciate the interface and control I've got over my zones, it just takes a few minutes for configuration changes to be processed. Yep, it's expensive but there are very few other options on the market that provide the same Erp category, which can be important in some instances.

That's helpful 😉 I'd be interested to know why they're crap and what else to use. The advantage with being internet connected is that the evohome fetches weather data from the internet which it apparently uses for modulation purposes. Otherwise I think the only other advantage is the use of the app for remote control. What you need to add to the evohome is a receiver together with a room thermostat for the additional zone. You then need an additional diverter valve controlled by the receiver. This way the receiver and evohome will open/close the relevant diverter valves to supply the zone. Your pump is then wired so that it receives a switched live when either/or/both zones demand heat. Adding the additional zone to evohome is simple, the plumbing may not be depending on how your system is designed. The expensive alternative is to add smart TRVs, but that may cause other unanticipated issues. On the side of Evohome critique: For me, one of the reasons i got an evohome was that at the time it was the only controller/programmer on the market that could support multiple zones including micro zones together with priority hot water (which is built into the programmer) together with load and weather compensation. It's not intuitive to set up and the problems I've found with it aren't entirely down to the controller but how the boiler manufacturers have decided to implement opentherm and heating/hot water controls as part of the boiler design, some of which come with several limitations. It seems that nowadays the boiler manufacturers are developoing their own systems to plug into the boiler that are easier to set up and guaranteed to be compatible. For example, I just fixed a problem with a Vaillant boiler with Vaillant's own controller where the heat curves had been set too low by the original installer (who had actually even replaced the first controller so there were two of them by the boiler). With the correct heat curve, the Vaillant's modulation is very refined with the built in weather compensation. Unfortunately, Honeywell Evohome doesn't like to give the installer too much configuration access so it's difficult to know what it's doing but in other ways this makes it simpler to set up in the first place for a basic setups like s-plan/s-plan+ with load compensation as you simply follow a guided setup procedure.

Thanks! Yes, I'm currently booked on for some of the heat pump modules starting in January. They keep on adding requirements to the courses though and if I couldn't book the courses directy with my current training company, the new requirements say I need 3 years practise to get onto them - but I'm sure providers might turn a blind eye to that with the promise of money. There's definitely been a bit of upping the bar for the MCS training programmes lately with a separation between installer and designer courses and qualifications, which could be either a good or bad thing depending on how you look at it.

Don't know about that but knowing me I'll probably end up doing it just because I'm interested and it might make my life easier at some point.☺️

Thanks, yes that wi be handy. As we moved to this area to do the project, we didn't know any trades which is such a risk. I think that's part of why I just did it mysef in the end. I wish I knew a short cut to this, although I'm starting to find the suppliers who make my life easy with good ordering facilities and local delivery. They might cost a few quid extra but the convenience factor is so good. There were a couple of merchants I tried to begin with where everytime I went in either to order something or pick something up, there were a couple of plumbers leaning on the counter talking crap and asking the most ridiculous questions while other staff members come and go without even acknowledging my existence. 45 minutes later I escape wondering whether those plumbers haven't actually got work to do.... it's like walking into a hell like dimension!

I've installed the Honeywell T6R now a couple of times and really like it. Good for Opentherm too, if your boiler supports it. You can by it single channel for heating only or with heating and hot water. Honeywell technical support is excellent too, at the end of a phone line with a video link facility too if needed. App used to be quite clunky but I think they've recently updated it. It's Homekit compatible if you're in the Apple ecosystem. The only downside for some is that it needs to be plugged in and won't run on batteries. https://www.resideo.com/gb/en/products/comfort/thermostats/programmable-thermostats/y6h920rw5031-smart-thermostat-wall-mount-kit-with-hot-water-uk-am-pm-y6h920rw5031/ Probably overkill, but if you want to go full on then the Honeywell Evohome is great and is openthern and heatpump compatible with the right receiver, but it takes a bit to navigate the settings and get it set up right - well, that's what I've found with a priority hot water set up, which it sensibly supports. Mine's on a simple 2 zone heating setup now with PDHW. https://www.resideo.com/gb/en/products/comfort/thermostats/smart-thermostats/atp921r3100-en-nl-fr-thermostat-pack-atp921r3100/

What seems to be aeons ago I started my self build - a bungaloid conversation which pretty much ended up as a full newbuild with a few remaining old walls because we couldn't change the planning for newbuild when we found out how bad things really were. We're weather and water tight and this summer finally moved out of the caravan into the house which still needs lots of work. We're still on temp electrics with extension leads everywhere! Athough we've had hot water for a while, I'm installing rads this weekend to give us some heating. The last couple of days has just brought the house down to a little chilly and my wifes wants some comfort. Anyway, to the moral of the story.. I had no building experience before taking this project on and I've done everything myself so far. When it came to the heating system I applied what I've now learned is a common self-builder trades scepticism and decided to do that myself, especially when I saw the prices involved. Our budget had already been hit because it was set for a 126m2 conversion and then had to now cover 196m2 so the truth is we ran out of money especially due to recent material price inflation. Mid Covid lockdown I decided to embark on a Gas Safe training course and after 18 months passed my ACS and installed our gas boiler, following which I've registered with Gas Safe and started up a small one man band to earn money to complete the build. I'd never even dreamed of going in this direction in my life so it's all down to doing the self-build. Surprisingly I've been run ragged by work, almost from the off and I've recently done 2 fairly major installation jobs, at least for a newbie. Doing this work has meant I've had to learn a completely different mentality which has beena bit of struggle. For example, trying to source materials and products at the best price is just too time consuming. Trying to make everything up myself instead of buying packaged/complete products has gone out the window because when customers are paying for my time, it actually ends up more expensive, both for them and for me - for example, making up my own ch or water distribution manifolds versus buying ready made manifolds. Buying for convenience has become so much more the order of the day. It's also incredibly difficult to balance quality and cost for the customer - I'm torn between trying to be perfect in the work I do and the associated costs to the customer. It's difficult not to drop standards in the rush to finish a job when the customer wants it done and when seeing the poor standards of so much work out there, even in such a regulated area like gas.. This has given me such a different perspective which is also changing the way I continue to build my house. Maybe I won't try to get everything so perfect and actually appreciate more convenience even if there's a minor financial cost to it. I might even get some trades in to help me finally finish the house off!

Yes, he's very good. Hope he doesn't go the consulting route, too good on the tools and it seems like he enjoys it.

I know, I was being slightly facetious because as per usual the elephant in the room is being avoided - it's all about consumption. Yes and yes. I'm still completely bemused by the continued circular rhetoric. The problem isn't technology, it's the political, cultural, economic, social and behavioural systems we've constructed and they seem to have more inertia than anything else we've come across. I agree. I also knew a farmer who harvested a lot of heat by burying pipework within the mounds of manure - used to get a reliable 60C all year round coming out of those pipes.