marshian

But it’s not being used as a buffer - it’s being used as a volumiser - useful link tho will read it properly later I considered fitting a volumiser with my old boiler to aleviate some of the short cycling issues I had (resolved instead by replacing the boiler with one that had a far better turndown/modulation) My intention was to fit it to the hot side so after the boiler hit the overheat limit the volume of water that needed to pass thro the rads before the restart temp was reached would be higher than the circuit without a volumiser but I had a flow rate of 10 lpm so With a few rads in circuit and the volumiser the total volume before the return temp dropped down to the flow temp (aka boiler restart time) I would have had maybe 6 or 7 mins of coast rather than 3 mins. However once I worked out the valliant/glow worm anticycle settings I could force the boiler to wait so no more need of a volumiser

Oh that's odd - I would have expected the volumiser to be on the hot side of the boiler not the cold side but I guess it doesn't matter

Thinking about it that's a heck of a circuit temp drop in 3 mins 65 deg down to 50 (ish) Have you got an ABV in the circuit?

My Heat only 16 kW 100-W Viessmann (so 3.2 kWh min output) when OAT drops to 0 deg C will happily run for 100 mins each burn at a flow temp of between 30 to 32 deg C Return temp is 24 to 26 Deg C

@JohnMo has an ATAG from memory

If in 60 mins you have 30 mins of burn, 3 mins of flame out and then another 27 mins of burn (in the hour) I would not call that short cycling - but that's just me............ If you had 3mins of burn and 3 mins of flame out and that process is repeated throughout 60 mins so that it's 10 burns in that time I would call that short cycling and badly short cycling at that. Ahhh explains it My question is if the rads are rarely used why are you using an elevated flow temp much higher than the floor needs and mixing it down - why not set the flow temp much lower (or as low as you can get it - like 45) it makes no sense to me to heat the circuit to a higher temp than the circuit is set too If the rads are required due to OAT being low then just increase the flow temp when the rads are required I'm not sure you need to do that based on my comments above Incidentally I'm all rads no underfloor and my boiler is currently at a flow temp set point of 29.4 deg C, since midnight last night (or this morning depending on your viewpoint) with the heating demand being 24/7 with no setbacks the boiler has been on for 780 mins - it's fired 21 times today with an avg burn time 37 mins. I have no volumiser or buffer as the circuit size is 130 Litres with 100 Litres being the volume in the rads and the boiler will modulate down to 3.2 kWh

Only if you want too - but towel rails are normally bypass rads because towels take longer to dry and bathrooms with towels over the rads take longer to heat. If you do fit them with TRV's you'll need to make your ABV less restrictive If you are happy the valve isn't allowing flow thro it due to an aging spring and the temps are very different either side then - my ABV has a scale with a number of points on it from 0.05 bar to 0.5 bar and it takes about thirty turns to go from 0.05 to 0.5 bar so I'm not sure how one with 0-5 numbers each 60 deg apart would work - I've tried google image search but not found anything similar Not sure why the focus on 12 Deg but I've said that before OK get a plumber to look at it It should only be a similar temperature to the water circulating thro it Seen them and responded

Quick fire questions Boiler flow temp still 60? All TRV's (where fitted are wide open) for a decent period of time say 30 mins after heating first came on before you took the readings? Because I'm now checking everything - You took the readings in the warm up phase - ie not when the rooms were up to temp and every room was cosy? Still don't know why you are trying to target 12 Deg delta on all the rads? Also don't know why you can't understand a really simple point The "hot" end of a rad is the "flow" and the "cooler" end is the "return" It doesn't matter if the hot end has a TRV or a lockshield at that end it's still the hot end therefore the flow - when you insist on putting the higher temp reading as the return value and the lower temp reading as the flow it makes no sense whatsoever. In the case of K1, Loo, Hall and Bed 4 you are declaring that the water in the radiators are being warmed up by the temp in the room because the return is higher than the flow - if that is the case then I think your room temps are too high

I might not be following but you've only got the volumiser (Buffer) in the underfloor circuit and one rad - not the rest of the rads?? I had huge issues with my glow worm boiler cycling (24kW - min output 10kW * see note) house heat loss after improvements 4.2 kW at -2.4 Deg C any warmer than that and it was going to cycle - shoulder season it was 3 mins on 3 mins off What I found helped was the anti cycle setting (on glow worm it was also related to flow temp) - does your boiler have that parameter - because if it does you can basically force the boiler to wait longer between burns so the circuit cools more. Obviously if the house isn't getting warm because of the anti cycle parameter then you need to reduce it but I found it very useful in managing the cycling issue Note * on initial fire it was throwing 85% of the max at the circuit so if the circuit was small it was overshooting and shutting down

I do it all the time when decorating no leaks or issues - obviously only works with conventional rads (fed bottom in bottom out) and not towel rails or vertical rads but that's life Only one rad in the house has no pull up clearance so I can't on that one but all the rest have a good 5 - 10 mm of "pullupability"

I reckon with a few rads always in circuit and no TRV's you might get a better drop on the return to the boiler with a tighter ABV If you don't get a better return temp and you know what setting it is now you can always put it back to where it was - you can't really lose??

That would be good..... What setting is the ABV now?

i couldn’t see the heating coil when I cut the top off once I’d cut the coil connections and pulled it out this was was left inside

I'm not a self builder (just a very hands on DIY'r who would like to self build one day - is it OK if still come ) but you make a good point very well

@John Carroll would probably be able to tell you what that circulation pump flows but on Pump Speed 3 it should be more than enough to cope with a big circuit of 19 rads TL:DR - might be worth checking / cleaning pump internals?? Long Version I've just had a thought (based on my experience a couple of years back) My CH circuit always ran on PS 1 (Pump Speed setting one) ie the slowest setting on the pump - gave best DT's at the rads - the house warmed up quickly and all was good in the world (I didn't have WC but ran a fixed Flow temp of 55 Deg C because below that the HW tank wouldn't heat up in the time slot) Only when it was really cold did I bump the pump speed to 2 rather than turn up the flow temp. I didn't like PS 2 because it circuit was noisier and Mrs Marshian is a stupidly light sleeper and circuit noise wakes her up. Then one winter the house wouldn't heat up as well and I had to turn the pump speed up to 2 when it wasn't really that cold outside. I really struggled to understand what was happening but eventually put it down to an aging pump (20 years old) Then when it got really cold I needed PS3 - something was really wrong. So I isolated the pump, removed it and split it This is what the impeller looked like Yeah that's really not going to help move water I have a magnaclean in circuit it never pulls much out of the system - this is typical after 6 months However there was one thing I missed - the magnaclean is after the pump not before it so protecting the boiler but not the pump So I cleaned all the vanes out on the impeller Yes I know it doesn't look like new but the magnatite I scraped out was a good half an egg cup worth. Pump back together and guess what - Pump Speed 1 was absolutely fine again - no system noise, warm house, happy wife = happy life. Next time I did some work to the CH circuit I swapped pump and magnaclean unit so it now protects the pump as well as the boiler.

Isn’t that gonna be a bit “sweaty” I do like the high Viz idea from a guessing who is part of the meet up - but I wouldn’t want to wear one all evening

Well @Dee you need a bit of help and she or he or it it matters not - I'm a he but it doesn't matter either way - you still need help Come to the Crown we can say hi and we continue the conversation in real life

He She It - Apparently gender can be fluid these days so I'm a she, a he, an it but best of all I'm a banana split

Working thro stuff always helps From the temps I'm not sure it's open at all But then again I'm not sure on the measurement process As @Dee has a couple of rads open all the time I agree - shut the ABV and see if it allows the system pressure to rise and the cold rads to warm up Good point - I forget older TRV's don't like being installed in the wrong flow direction - at low openings the flow forces them to close Anyway thanks for the contribution - I think @Dee thinks he's all alone but you are never alone in a forum community it's what keeps them alive

It's not meant as an insult - just a comment - no malice in the statement It takes me ages to get my head round something - electrics especially

That doesn't make sense but lets run with it What's the maximum number on the ABV - ie highest?

Spot on ^ We live in a stupidly hard water area - kettles last at best 2 years and anything that gets in contact with water has water marks all over it When I replaced my 115 litre copper HW tank in 2011 (old one had been in since house was built in 1982) I drained it down and disconnected it - I could hardly lift the damn thing and it took two of us to carry it down the stairs The local scrap dealer would give me a good price for copper but stipulated that it had to be cut open and any scale removed before he'd weigh it and give me cash for it I could not see the heating coil for all the scale inside!!!!! I've got a picture somewhere of the inside of it!! I fitted a water softener after that and now the glass and tiles in the showers stay super clean and the taps don't fur up Kettles still only last 2 years max but we don't use softened water for cooking or drinking

You can be whoever or whatever you like these days - apparently!!! I've just worked out how to get a profile picture up - so now everyday is banana splits day

OK - so almost certainly an ABV Well we need to establish if the return via the ABV is warm first 🙂 Have you done that yet??? If there are numbers on it it will probably either relate to operating pressure in which case the higher the number the better in terms of shutting down flow or just be a number scale in which case I don't know - you'll just have to experiment Here is what I'd do if I don't understand the impact of something like this Firstly boiler needs to be firing - your flow temp is 60 deg - that's enough to burn so be careful with hands on pipe tests First with hands on pipe above and below (or a temp clamp) wind the dial round to the max number Does the pipe below feel warmer or cooler If it feels warmer then the number shown equals more return If it feels cooler then the number shown equals less return Then repeat the other way wind the dial to the min value That should tell you what number to set it too (The number that makes the pipework below it cooler) PS It's lefty loosey 😉 sorry Please don't do that (in bold) - the hot end is the flow the cool end is the return it does not matter which end the TRV is the flow and return and it's path thro the rad doesn't change Nearly all TRV's have a double arrow on them - they work in either flow direction. All lockshields don't care either - they can be on flow end or return - if fact remember before we had TRV's we had a valve with a knob on one end of the rad so we could turn it on and off or slow the flow (the other end would have the same valve but with no knob on it acting as a flow restrictor when balanced) I'm none of those things BTW - I just have an interest in getting my heating to perform at it's best and made quite a few errors on the way. "Experience is what you get when you don't want it" I don't think they've given up on you but it's clear to me you take a little while to grasp / understand stuff so you need a little more explanation than just "do this"