alfaTom Posted March 6 Posted March 6 I made a previous post where I got way too far into the weeds on satellite manifolds. To try and clear things up and provide a bit more clarity (as well as help anyone else in a similar situation) I thought I'd post a new thread with the current plans for plumbing in our property. Earlier this year I relaid our water supply and put in a 32mm feed. It's probably OTT, but the cost difference between 32mm and 25mm was so close I decided to go for the larger bore. The house has had all old plumbing ripped out; it used to be on a copper branched system and was gravity fed. I'm going to replace this with a manifold system to each wet room, and the DHW will now be via ASHP & UVC rather than oil boiler and VC. The water feed rises in the plant room where the UVC will be sited (with ASHP on the other side of the wall to UVC) to try keep things together otherwise I'd have a few runs crisscrossing the plant room. Water feed to UVC/manifolds: Tee with 15mm feed to outdoor tap with separate stopcock Main 32mm stopcock with reducer to 28mm Tee with 15mm feed to downstairs toilet and sink (This is because they are the other side of the wall to the feed so easy to supply) 28mm continues to control group (3.5/6) Cold water from control group is then split into hard water and softened Hard water heads to manifold Other feed to water softener (yet to confirm brand; don't really care about single/dual cyl or mech/elec function, more about not losing that pressure.) Softened water will then be sent to each bathroom in 15mm Manifold supplies and their estimated distances: Cold (Hard) water manifold Name Pipe diameter Pipe distance Utility Sink 15mm 8m Kitchen Sink 15mm 3m Cold (Softened) water manifold Name Pipe diameter Pipe distance Downstairs shower 15mm 2m Kitchen Dishwasher 15mm 3m Utility Washing Machine 15mm 10m Family Bathroom (Bath/Shower, toilet, sink) 15mm 8m Guest Ensuite (Shower, toilet, sink) 15mm 9m Master Ensuite (Bath/Shower, toilet, sink x2) 15mm 12m Hot (Softened) water manifold Name Pipe diameter Pipe distance Downstairs shower 15mm 2m Kitchen Sink 15mm 3m Utility Sink 15mm 8m Family Bathroom (Bath/Shower) 15mm 8m Family Bathroom (Sink) 10mm 8m Guest Ensuite (Sink) 10mm 9m Master Ensuite (Bath/Shower) 15mm 12m Master Ensuite (Sink x2) 10mm 12m (Note: No Guest Ensuite hot for shower as it is electric) For the above I am mainly concerned on pipe distance for the hot feeds, with the master ensuite being the furthest away at about 12m of pipe. I've split the sinks into a separate 10mm feed to try get hot water there quicker for handwashing etc, but otherwise I think the rest is ok in 15mm. I've ditched any thoughts on HRC and decided to keep it simple. All pipework will be run in Hep2o where possible. I could reduce the manifold size further by grouping the utility sink & washing machine, and the kitchen sink and dishwasher feed into shared 15mm runs but it should be easy enough to run a second bit of pipe if needed. Most joists are new posijoists so easy to run the pipes, just a bit interesting to clip to. Have I made any obvious mistakes? There will be isolation valves in various parts to help with maintenance so haven't listed them (i.e. control groups, softener). Only other thing I can think of currently is if manifolds should be fed from both ends or not to help when more than one run is active. Thanks all!
Bonner Posted March 7 Posted March 7 Normally 22mm to baths. 10mm is pointless IMO, more expense and complication with little or no benefit. Make sure isolation valves are full bore.
BotusBuild Posted March 7 Posted March 7 22mm to a hot a cold manifold in the plant room, then 15mm to each room/item. Two pairs (H&C) to each bathroom, a pair to the kitchen, a pair to the utility. Just spent 5 weeks camping out, and the rain shower had plenty of water.
JohnMo Posted March 7 Posted March 7 4 hours ago, BotusBuild said: 22mm to a hot a cold manifold in the plant room, then 15mm to each room/item. Two pairs (H&C) to each bathroom, a pair to the kitchen, a pair to the utility. Just spent 5 weeks camping out, and the rain shower had plenty of water. Mine is way simpler than that. Manifold in centre of house, 15mm from UVC to manifold, one 15mm hot to each wet room, then branched. Similar for cold. 22mm just slows delivery of hot water not really needed. Why an electric shower in guest ensuite?
Nickfromwales Posted March 7 Posted March 7 Get rid of the electric shower, it’s a choice you’ll live to regret. UVC will have an electric immersion for fail-safe hot water. Thermoststic mixer showers will speed up or slow down, when other outlets are opened when showering, but the cartridges will balance the flow to keep the temp stable. In the same circumstances, an electric shower will just slow down, go red hot, and then abruptly shut off and deliver cold water (unless it’s a 7.5kw one which I can piss faster then). 1
alfaTom Posted March 7 Author Posted March 7 Thanks all, some good points and looks like I've simplified compared to previous plans. I think 15mm runs are likely to be fine, even for the furthest distances. All the information on this site is a blessing and a curse as I wouldn't have known about half this stuff if I hadn't been reading up 😁 Thought the electric shower would get people asking. When we first started the work it involved taking the old oil boiler out so we had no hot water. Electric shower went in so we could still shower, and it's not worth the effort of removing now given how often it'll be in use going forward.
Nickfromwales Posted March 9 Posted March 9 On 07/03/2025 at 15:10, alfaTom said: Electric shower went in so we could still shower, and it's not worth the effort of removing now given how often it'll be in use going forward. Ah. Ok. Sorry, I thought it was part of your plan eg to be installed.
G and J Posted March 9 Posted March 9 Is a pressure balancing thingy needed somewhere to reduce cold pressure to match the hot pressure? Presumably it’s only the showers that such a thingy needs to serve…
alfaTom Posted March 9 Author Posted March 9 5 hours ago, Nickfromwales said: Ah. Ok. Sorry, I thought it was part of your plan eg to be installed. I'm not that mad 😁 when we moved in it was an old 7kW thing. New one is a fancier 10kW thing with a wee touchscreen, this was the finished article. Mrs had a requirement at least one room in the house wasn't a horrid old 70s maroon bathroom... 4 hours ago, G and J said: Is a pressure balancing thingy needed somewhere to reduce cold pressure to match the hot pressure? Presumably it’s only the showers that such a thingy needs to serve… Yes - that sits as part of the inlet control group block - one feed to UVC and one to soft cold manifold. I do need to add in drain cock and NRVs in still that I didn't mention. 1
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