JohnMo

So your boiler has a minimum output of a out 10kW, which is pretty huge. So you really need most of your radiators on, while you try to run the UFH. Bringing down your flow temp will help, as it will slow down the system and reduce radiator output, so thermostats cycle less. Tell us more about what is controlling your radiators?

If you count is 1 full cycle in under 10 mins, you have issue to fix. Your boiler should start, modulate down and run for a prolonged period.

100L cylinder with a 32 kW boiler takes under 4 minutes to go from 45 to 60, as it's only 1.75kWh heating capacity in the cylinder. So to get a useful run time you would need several hundred litres. Hence my recommendations

Remove actuator from valve and truly to rotate the valve with your finger. It should be easy to move. Manual valve is an isolation valve, so likely to have a handle on it. May look similar to this Do you have any drain valves upstream of the UFH but after the motorised valve. Will look like this?

1. I wouldn't bother 2.Not sure what you will gain from this 3. That just makes stuff way more complex, and sure it will gain you much. Read a few Baxi datasheets and manuals and they don't seem the most sophisticated of boilers and not the best output turndown. With this in mind, you need places to dump heat, as your summer house will struggle to a absorb the heat on offer and I would suspect your boiler doesn't run for long and has plenty of cycling, which will ultimately reduce life, but use way more gas than needed. Turning down flow temp could lead to issues with cylinder heating, so do it small steps, you need to ensure the cylinder heats in one long boiler run, not lots of short cycling, which will be the result if you trim heat too much. The ideal way to run UFH is low and slow, so I suspect the UFH mixer could be turned down. To help the boiler out, need other parts of your heating system open. This is basically a recipe for boiler short cycling, higher gas consumption than you could have. So timings I would set all the same, run whole house a little warmer. Next steps and questions Does boiler accept opentherm control? You really need to run the heating system differently, so priority domestic hot water, opentherm is an easy way to implement this. So basically you run one flow temp for cylinder heating and another for central heating.

Few things, motorised valve not opening valve. A manual valve closed in that circuit. UFH pump not starting UFH mixing valve stuck and not sucking any new hot fluids in.

There climate is a lot different from ours, they are hotter in summer and way colder in winter, which is way better than the just above freezing, high humidity winter climate we have, for ASHPs. So defrosts are way less of an issue. Then it's just a matter of sizing correctly.

Why not when it's easy to do, actual boiler efficiency has little to do with boiler model more to do with how it's plumbed in and controlled. You could probably save a good 20% on heating costs. And get way better hot water performance. So choose your combi of choice, but make sure it's controlled via opentherm, not on off thermostats. But ideally has plenty of turndown so min output is low. Not the best boiler out there, pretty poor turndown, with a min output of about 10kW, so boiler will cycle a lot at mild temperatures. The best will turn down to under 2kW. Can only run at a set flow temp. So not the most efficient by a long way. Hot water flow rate is 11.5L minute. Just looked at my old boiler and it did 15L minute at the same 35 Deg temp rise. And had a turn down to half the one you are looking at. I would look at other makes and models.

Some simplification sounds the order of the day. A couple of radiators kicking a huge boiler into life for 5 mins isn't an efficient way to run a heating system. Will wait for the additional information requested above.

But would life be worth living afterwards, "I would of or I wouldn't of" being mentioned many times, comes to mind

Solution is simple - get rid of the blockage. Either remove down pipe and unblock or leave in place and blow out debris with a hose pipe from the top. Maybe while your up there clean the gutters if that's what feeds the down pipe. Most window cleaners now do a gutter cleaning service, get them cleared every year, or if plenty of trees around more often. Fix the problem, don't cure the symptoms.

What in the rest of the heating system, as I assume you are not using 32kW just to heat a garden room?

Nearly twice the cost of the UK! That's expensive heating, a time of use tariff and direct electric heating would cost about the same when you add in boiler efficiency.

When I used a plumber, we used a firm that employed plumbers, not lone self employed ones. We generally had the run around, just like you until then. Learn what to do, it's not really that difficult, you don't even need to solder these days. Easy DIY stuff to use 1. Hep2O, plastic pipe and push fit fittings. You need a cutter for plastic pipe and that's about it. 2. Tectite push fit for copper pipe, a selection of fittings for copper pipe, you cut the pipe with a proper cutter, and the fitting simply push on just like Hep2O ones, but these are metal. Drain pipes, solvent weld or compression joint, just remember they are generally different sizes, so don't generally mix, you choose a system and stick with it. Then it's a matter of correctly sizing the pipes.

Why, they give you 15p, then immediately charge your next door neighbour nearly double that. Pretty good money making scheme.

But that isn't fully correct, because it doesn't take into account the gas standing charge, which goes when you remove the gas meter. So if your house consumed 6000kWh of gas per year your pay £377 for the gas plus £125 standing charge. So your 6000kWh cost you 8.35p per kWh, based on standard prices. Electric is 26.35p per kWh. So real spark gap is 3.2, not 4.2. And the above doesn't account for the approximate 80-85% efficiency of nearly all gas boiler installs. So piss poor reporting by Nesta

Not to any scale, drilling to tie back just keep existing facilities ticking over for longer. There is loads of oil out there and routing pipe back to existing back to an existing facility may not be easy or cost effective. It's playing at it

But "In the Autumn Budget, it was revealed that the current iteration of the scheme, ECO4, would end on 31 March 2026" So you have 4 months for Eco4, but the BUS grants stay in place for now. So don't seem to be affected.

Early bird, procrastination etc...

There is a single pipe, between wall units and island not on drawing but on photo, floor temp is low - you don't notice it unless really cold outside, talking -9 for a day or 2. Then you only notice it, but only with feet at the kickboards. We have 100mm concrete screed, so the temperature spread is pretty wide away from the pipes. Very unlikely the rooms will get moved about as whole is there for the views, which disappear with the bed on a different wall or dining are at the other side of the room. I found it ok. You basically build the house in the software, so you need U values, window sizes etc. Its good for balancing floor outputs, I got mine to within a few Watts for each room, so system balance is good out the box. I found later wife had very different ideas to floor covering for bedrooms than me, as a result bedroom output is a little low than planned, but works ok. Nice wool carpet insulation.

I would work through 1 room in detail and check his calculations. A lot of plumbers will stick a finger in the air and use a rule of thumb, you definitely do not want that. Not sure what units he is using but seems to be BTUs, if so I suspect a rule of thumb is used..

I used a Henry attached to a concrete floor grinder, many bags later still going strong. Several years later still no issue. Get one with HEPA filter so no dust makes it's way to the motor. Several years ago used a Dyson to hoover up some plaster dust, 10 mins later it went bang. Not covered by warranty as it was being used for a DIY task!

I have renovated a couple of houses dating back to a similar period of yours. I have done a DIY floor renovation and got the professionals in. If you want good wooden floors get a professional in, he will get the job done, make a good job of it, but seek recommendations or view his work elsewhere. If you are going to carpet And if the ground floor is a suspended floor, be careful just having a wooden floor as you may just get a lot of cold drafts coming from all the gaps in the floor boards. So good high tog underlay and carpet will save on your bills for heating.

Yes No it may not reduce it, gas boiler efficiency may increase, but downwards heat losses may wipe those gains out, plus a little more. I would find a local heat geek engineer or someone used to low temperature heating systems and get him to quote for installing or designing an efficient system, based on the boiler you have.

Sorry a miss type, should have been loop flow rate. Text should have read - see bold correction "If all room are not warm enough trim flow temperature up. If you get to temp really quickly and it overshoots trim temps down a little at a time. If the odd room is too warm decrease flow rate of loops in that room - opposite in cool rooms." Explanation of what is happening. A floor heat output is governed by the means flow temperature, so the difference between flow and return temperature. Adjusting a loop flow alters the differential temperature (dT). Reducing the flow increases dT, example. Start point dT 5, flow 35 return 30, mean flow temp is 32.5 degs Flow reduced, dT increases to 6. Flow is still 35, but return temp is now 29. Mean temp is now 32. So floor out is reduced and room temp comes down