Thanks for that. Yes I missed the HW valve on my excellent drawing.I like your diagram. I'd do similar.
Needs a valve on the HW as you don't want that heating all the time.
No zone valves means local control at the rads and a central programmer.
3 floors is big, so pump on the middle floor, perhaps use a variable speed one to help modulation.
I'd do some check calcs for load swing from min (one rad) to max (all)
I'm answering this because nobody else has. I'd suggest professional design though.
I don't like combi boilers, especially for big houses. Too many compromises for my liking.
I don't like system boilers. I don't see the point of jamming everything into a tight box if you don't have too.
I don't like pressurised systems. You can't work on them and they are more complex than a bog std vented system.
Let the stoning begin.
I don't like combi boilers, especially for big houses. Too many compromises for my liking.
I don't like system boilers. I don't see the point of jamming everything into a tight box if you don't have too.
I don't like pressurised systems. You can't work on them and they are more complex than a bog std vented system.
From a professional angle, manifold installation requires bigger pipe runs as source is the manifold and final the radiator. Imagine a floor with 6 radiators- there would be 12 pipes from the manifold to the radiators. Now visualise these 12 15 mm pipes below a flooring with limited space.
Next a boiler. On a new system I would fit a combi boiler and an unvented cylinder. Solar panel additional to cylinder.
If house is a big one, woukd fit two combis to split the load, have done it before and worked very well so no single source of heat to fail taking the whole house down.
Convention and good option is to have all the controls where the hot water cylinder is. In fact there are hot water cylinders with MVs already installed.
Unless you have really old property, 22mm runs to each floor should suffice with finals and branches to suit. A 15 branch might even feed more than one radiator depending on pipe loop loading.
The combi would supply on tap hot water in utility and kitchen unless the hot run is long. Combi also has integral expansion vessel which you most likely have where the hot water cylinder is. Often the kitchen is on first floor and boiler in garage in which case the the hot water to kitchen tap from boiler would take a while to flow hot due to long pipe run
HiI had a large system like yours put in about 10 years ago. Vaillant 438 boiler, 3 zones (u/s, d/s, hot water). 28mm primaries from boiler, reducing to 22mm throughout the house and then 15mm to rads.
With multiple zones and a large boiler (in particular the vaillant, because of the pump head required to overcome the restrictive hex), a low loss header resolved many of my problems, including being able to spec 2 domestic CH pumps, instead of a large and expensive semi commercial pump.
I tried wiser for a while and for me it just wasn't effective enough to justify the cost. Unless doors between rooms were kept closed, you'd end up with the heat spreading uniformly across individual floors.
I would, however, highly recommend weather compensation and priority hot water with an unvented tank. Not only for efficiency but comfort too.
Hi
That’s interesting….how far did you run the 28mm primaries (doesn’t the boiler have 22mm connections). Reading up a lot don’t like the 438 we have. How does the low loss header with twin pumps work?
I’ve got the Drayton just as 3 channel at the moment, ordered a trv to test its functionality but may just leave it as each floor, I guess I have the option now as the hive trv’s are supposed to be rubbish.
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