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@@steves1460 we fit them all the time. As long as the subfloor is solid and they’re fitted properly then why not. They can be quite a time saver.

@@griffithsheating that’s a relief and thanks for the quick response!

yep. close coupled tee, emm1 extension box, 10K low loss header sensor and an esbe mixer & pump. jobs a good un. You wont need a mixer on the UFH manifold

@@griffithsheating thanks!

Is there no Tesla valve for maintenance on exspansion vessel on buffer?

Do you not need a bypass?

Wouldn’t you rather air air vent top of volumiser

@@lukeb6565 volumiser is piped like that. Prv on volumiser isn’t normal but it is a good a place as any to put it. No valve on exp vess. No need. We could have put an air vent in but doing the vessel like that was a neat solution. Plenty of air vents on the system otherwise. 😎

@@markfernandes2467 it’s not a buffer

@@griffithsheating Is there a difference then? What does a vollumiser do then and why did you use one of those?

@@markfernandes2467 yes. A buffer provides a hydraulic break between the heat pump (primary side) and the system (secondary side). So an additional pump is required for circulation in the secondary side. If the flows are poorly balanced between the primary and secondary side you get what’s called distortion where the heat pump may be delivering 45 degrees but the buffer is only supplying 40 degrees so the heat pump has to run at 50 due to achieve 45 degrees in the system. The upside of a buffer is that you can get away with murder on the system design and the heat pump won’t notice but your efficiency will suffer. There is a bit of dogma around buffers amongst the pseudo online big brains. They’ll decry buffers from the rooftops and smugly rip an install apart because it has a buffer. I have Viessmann systems running buffers with scops almost touching 5 after nearly 2 years. A volumiser is essentially just a big tube of water sitting inline just to increase water volume in the system to help with defrost volume or to increase compressor run times when it’s mild out.

@@antanasmastaras795 we’ve had more Telford cylinders fail since this one. The last one Telford made the customer buy a new cylinder and said they would investigate who is to blame and let us know…..well we all know how that is going to end don’t we…..warranty not worth the paper it’s written on and I would never fit Telford ever again.

3 years on and it hasn’t moved 😀 I went back to it a few months ago to unblock the trap as someone decided to pour their dinner scraps down it 🤔🤢

Ufh flow rate is set by the manifold flow setters and the rads can be set with either a flow balancer or flow setting rad valves. Or you could use what’s called a stad valve

@@griffithsheating Cheers it is a Grant Aerona with a low loss header only 9 rads the T1-T2 is only about 2-3 nightmare.

@@Allegedly2right bare in mind that your dt will only be at design (5, 7, 10 or whatever) when you are on a design day which is a day below zero degrees outside. Anything more than that the dt will narrow.

There were a few serious install issues on this job created by the original installers that would make a super low flow temp a bad thing. They fitted a GSHP with a fixed speed compressor just to ‘get the job done’ (grant money banked) when they should have fitted an inverter driven unit as specified. And they massively undersized the buffer. The hp was cycling bad enough already and having persistent high pressure faults, trying to run it at <45 degrees with the available system volume would make it worse. All my advice fell on deaf ears though and now I’m probably the bad guy 🤷

OK. Sorry to hear that.

It’s just Armaflex taped with class zero tape 👍🏻

We’ve done a similar split upstairs / downstairs cascade with a pair Viessmann vitocals. You will have better low modulation performance and ultimate control in this configuration in my opinion. Not sure you could open loop a true cascade as it would probably need a buffer I would have thought. There is nothing wrong with a buffer, not everyone is interested in chasing the last few percentage of performance. Its a central heating system not formula 1 car

😎👍🏻

Vaillant is better priced, easier to get hold of, easier to quote for, better manufacturer support, no need for indoor unit so fits in a smaller space and vaillant seem to know Their product better than Viessmann BUT the Viessmann controls on the 150a are superior to the Vaillant.

No blending. Just letting the heat pump do its thing unrestricted.

@@griffithsheating it makes sense, less expensive mixer station/pumps better savings. Is this your standard going forward then? Do you just run one stat for the whole house?

@@gerardfry4876 there is a wireless Vaillant senso comfort controlling it so you can either run it as a room stat or just off a curve with no room influence. Not sure how the customer will want to run it yet.

And if the pump on the HP can’t supply the index circuit with enough flow, would you fit a buffer then?

@@gerardfry4876 yes if my calculations are wrong I’d have to convert the volumiser to a buffer and add another pump.

Over 4

Sensocomfort

Sshhh don’t talk about the gas boiler or Kevin 🤫 we ran out of big clips. I’m not arrogant I’m just better than 99.9% of everyone else. I qualified 6 months ago so have a lot of experience.

Boiler was obviously part of the old system to be ripped out.....🙄........

to the bloke that needs an electric bender because he carnt pull a bend ' also pull youre head out of kevins ass and crack on with youre rad valves and tap washers Dick ' fairplay lads looks like you know what youre doing ' 💪💪

I was thinking more of minimum run times when it’s mild out. I have seen Arotherms ice up though even when volume seems to be ok.

Nope, the open loop system becomes the volume you need for Defrost, been installing like this for decades already.

@@kenbone4535 Specially with UFH you have lot of energy mass around in case you need any excess energy for defrost.

I’ve just had the 5kW version installed with identical 50L volumiser, my installer (Heat Geek Elite) confirmed it was not just for defrost cycle but also ensuring there was enough volume in the circuit to prevent the ASHP cycling as much as it might without it (due to size of my system aside from the volumiser)

Not required (it's not shown on the vaillant schematics at least) I don't use 2 ports or over heat stat on gas either if I'm fitting a Viessmann boiler with an ntc sensor on 4 pipe. G3 police haven't arrested me yet... 🚓

@@griffithsheatingBuilding Control would not give you a completion certificate with no 2 Port on the UVC here in Jockoland mate!!!

Let's just say we had a disagreement about the part L building regs 😄 They claimed all heating systems have to be designed to 45 degrees and I called 🐂💩 and 7 months later I'm still waiting for a BUS grant payment. I guess I'm not cool enough to join their club.

@@griffithsheating what did you design to? Sounds out of order to me

@@jacbisgood2221 designed to 55 due to rad space available but that's knowing the home owner is doing a load of additional insulation in the roof space and floor so will end up around 45/50 mark. It actually was finally signed off and grant paid today as it happens 😎

It's not a worry. I've done the sums. Insulation would be great in an ideal world but we don't live in an ideal world 😬

Not sure if the 250 is on sale in the UK yet. Viessmann are pretty bad at keeping installers informed what's going on with their product line up.

Hmm, sorry i did not mentioned that i am typing from Germany :) As i understood from datasheets, A150 is price/performance variant of 250A. 250a has a better coefficient value and more slient(66db vs 64db)

Aaaannnd 3 years later and the shower hasn't moved a mm and is water tight (I was back here last week repairing the trap as the tenant had damaged it trying to clean it )😎 Check that hubris at the door buddy

Cheets mate 😎 just size the 2nd pump to suit your index circuit. The hydronic gods will take care of all the other stuff. The worst that happens is that you get a bit of distortion. I.e. the boiler is running at 55 degrees but your flow temperature out of the secondary circuit is 50 degrees as it's pulling in return water through the CCT and lowering the flow temp.

@@griffithsheating hello mate, just got round to doing this on my system. I was wondering where you would wire the additional pump for the rads after fitting the cct. if I wire it to come on when the zone valve for the rads opens, then it'll run when just the UFH is calling for heat, since they share the same switched live to the boiler. but if I wire to the switched live from the thermostat to the rads, it'll come on before the rads zone valve has opened. I've got a bypass radiator to dissipate heat though so I could have the pump before the branch to this and the zone valve controlled rad circuit. what do you think? sorry for bending your ear on this, do you think I should use a relay?

@@UndisputableFact yep ideally you’ll need relays. I had the same problem. I can’t remember what I did to get around it I think I did something by taking the heads off the zone valve and using them as a pseudo relay of sorts……I really can’t remember….but it worked🤔🤨🧐

@@griffithsheating all sorted, I can’t believe how well it works! Ended up wiring into a dedicated ‘powered’ terminal when on central heating for the boiler I’m using. I did kimbo betty’s course a couple of years ago but decided to do it the ‘wrong way’ first to see how bad it could be- and in my boiler’s case, it was very bad indeed. Should have done this sooner! Thanks again mate, this has made my year. keep up the good work! :)