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Old gravity fed water system has been removed and a new mains pressured UVC system has been installed by the builders plumber. ATAG Gas Boiler, 250L Gledhill Stainless ES Cylinder plus expansion tank. Mains supply currently via lead pipe connected to 15mm copper. Static mains pressure about 3.5Bar at outside tap connected directly to mains via 15mm copper/plastic. Flow rate from tap 20l/m. System has 3bar PRV fitted. Cylinder has 4.5Bar/95C over pressure/temp relief valve. System is fitted on ground floor. Questions/Issues 1/ Should there be a Tundish fitted as there is currently none. The overp/t relief valve has nothing connected to it at all and would discharge onto the floor ?! 2/we wanted to be able to run 2 showers simultaneously and still flush a toilet/use kitchen tap. Currently B/room shower gives static pressure of 2.8Bar and flow rate of 10l/m (hose only) or just 6.6l/m(from shower head/flow destructor removed). Noticeably weaker than old gravity system with 3bar(2.5bar at 9l/m) monsoon pump. If another tap is fully opened upstairs, shower static pressure drops to 1.4bar. Shower flow drops to 5.5l(hose only), 4.6l/m(through shower head). Hardly likely to support 2 decent showers at once. So what pipework should the plumber have installed ? Is the problem the pipe bores used, the pipe bends and Tees, the cylinder plumbing, the pipe lengths ? Very concerned now that plumber hasn’t installed adequately and not fit for 20 year use. How to know what exactly is wrong and how to fix it ? PS Current Pipes in sequence… 20m lead into property 15mm copper stop tap 22mm copper to water softener (not yet fitted bypass valve operating) 25mm MLC pipe to cylinder/boiler area 22mm copper to PRV, cylinder, and 22mm copper hot and cold to first floor landing. Then 15mm copper feeds from the 22mm pipe to upstairs taps and showers. 15mm Tee, 3 or 4 15mm right angles to shower mixer.

My plumber is telling me I need to allow 100L per person per day (implying 400L tank), whereas my architect is telling me I should go for 300L because plumbers always over-specify. Our water usage pattern is as follows: The way things will be in the immediate future: we run one bath for both kids to share every evening - the bath we will have requires approx 125L of (blended water); we each shower for about 12-15 minutes in a fairly good rain shower, usually in the evening but occasionally in the morning. No idea of water usage for that. once or twice a week, I run a large bath (250L of blended water required), instead of the daily shower. In the future, things for us adults will stay the same but I imagine the kids will eventually want to bathe separately, so that will be an extra 125L per day of blended water and when they are teenagers I'm assuming showering will replace bathing. So what indirect unvented tank should I go for: 300L or 400L? Struggling to understand how much I should plan to heat on an everyday basis and how often I should use the "extra hour" feature. For example, would a 300L tank suffice as long as for my once or twice weekly giant bath I used the extra hour feature. How does washing up impact the above? We mostly use a dishwasher, but there are still large pans to do in the sink etc.

So I have stripped out all the existing pipework, back to the incoming main, on my major renovation extension. I have an overall concept of what I am trying to do gleaned from reading this forum, but have many questions! Trying to make sure I am on the right track before buying all the kit. I have three bedrooms all with ensuite WC, basin and shower, one has a bath. Heating is UFH on ground and lower ground floor, radiator in each bedroom, and towel rail/radiator in each ensuite/bathroom. Downstairs also has a bathroom with shower, WC, basin. I have mains gas. so the concept is to have a new gas system boiler, an unvented cylinder and run UFH, heating and hot water, all from the tank. Is this how it works? The tank I am looking at is from AVChttps://www.acv.com/gb/professional/new_product/06627401-465/smart-e-plus-240#tabspace=unit&tabid=diagrams, and is a tank in tank system, so using the primary heating water as a buffer for the UFH and radiators. Using Hep20 from a manifold for hot and cold water, and run the upstairs radiators from another manifold upstairs. I know I need a double check valve and stop cock on the incoming main, and a PRV before the tank, the tank comes with a mixer valve. After that I am not sure what I need I have seen some on here use one large, valved, brass Hep20 manifold say in the utility room next to the boiler and tank, to feed everything, others have used sub manifolds for each room, using the much cheaper, plastic, non valved Hep20 manifolds. Is this purely to save money, I like the idea of being able to turn off individual consumers from the manifold, but unsure in real life how often this could happen, cost difference is considerable, but then it is a one off cost. Control wise I am planning on using Heatmiser Neo thermostats on each zone, and a Neohub and their wiring centre for the UFH and also for the radiator manifold circuits. Boiler was looking at Veissman Vitodan 200 series but unsure on sizing, these are available with weather compensation, but will this work with Heatmiser, how do they talk to each other? Was trying to find modulating thermostats but Heatmiser don't offer them. Also unsure on UVC sizing, as it appears I could run a smaller tank, 210 litres, if I have a large enough output boiler to reheat it fast enough, or is it better to have a larger tank, 300 litres and a smaller boiler, also have a solar array of 3.7KW so was hoping to use a diverter to an immersion in the tank for all excess solar. I apologise for so many questions, but feeling a bit overwhelmed by everything.

Hi everyone, a quick intro to say hello. More a renovator than a self builder and very much at the end of a project to make an 1870s Bristol house suitable to keep us here for at least the next ten years with a growing family. With a 2 year old and a now a two week old I had as an objective to reduce the carbon footprint of our energy use. The project was principally a single story extension to make a kitchen diner in addition to various changes to other rooms such as a bathroom with some walls coming out in the process. The opportunity was there to move the boiler and having had one too many showers turn cold with another tap being used, I decided it was worth doing something to the water system in toto. This is where I owe this forum and certain contributors a huge thank you as I learnt a great deal from them whilst trying to decide where to go with the spec although it didn't quite follow the original plan. The house is a narrow terrace with a couple of rooms on each of three floors and is topped off with a butterfly roof so less than ideal for solar. So why join the forum now? Well the principle threads I followed were around hot water and we've ended up with a 4kw array on the more favourable pitch, a Powerwall 2, and a Mixergy tank. This last part I see mentioned here quite a bit so wanted to offer a bit of user feedback to those considering one if that might be useful. There was much to'ing and fro'ing before arriving at this setup and the original intent had been a Sunamp Uniq 9 or larger. Various things conspired to drive the spec as it stands and we're only in the first few months of use. Very much learning as we go. I hope this finds everyone well in these times. Best, Billy

Needing to focus on my next project after my UFH fiasco and being in a holiday rental place where the DHW is very hit and miss reminds me that I need to get some specs laid down before I start ordering stuff! Having read so much over the past couple of years, I feel a lot more informed but also a bit bamboozled at the same time. UVC or TS, buffer tanks, what size..... So my main questions (so far): 1) what type of gas boiler to go for? 2) Thermal store or UVC? 3) Buffer tank needed? My setup will be: 4kw solar PV Mains gas 2 UFH manifolds (upstairs and groundfloor - so I can choose the flow temps accordingly to get the maximum comfort levels) Room stats in all areas 2 Bathrooms (2 showers, 2 baths) MHVR Although not going to be a passivhaus, I’m hopeful it'll be a bloody whole let better than your standard newbuild: 2 SIP extensions 300mm EPS floor insulation 3G windows/doors 100mm EWI on existing house DHW requirement: 2 adults and two soon to be teenagers (so they will hardly wash reducing the DHW figures a bit) 2 morning showers 2 evening baths Hot water for washing up (though may get a boiler-type tap for most hot water needs in the kitchen) Occupancy: Wife and kids out and I although I work from home, my office will be one of the sheds out the back so main house can either be set to off or very low temps during the day. UFH demands: Groundfloor: Water volume: 129L; Estimated loading: 9.45Kw Upstairs: Water volume: 25L; Estimated loading: 2.03Kw BOILER QUESTION: Before I start getting plumbers out to fit a boiler system, I’d like to get people’s advice on whether to go for system or combi. Combi = don’t need a water storage cylinder = no need for cistern in loft = combi boilers don’t supply enough hot water = better to use a separate cylinder for the hot water supply. = combi boilers can be quite noisy. System = Store hot water in a cylinder, so they can feed several outlets at once at mains pressure. = no need for a cistern in the loft and the expansion vessel is built in. = Flow rates will be high as water is delivered at mains pressure, and hot water is instantaneous. I'm thinking to go for a system boiler at this stage (easier/quicker install) and then to use excess PV with the cylinder. THERMAL STORE OR UVC? My thoughts so far are to have a 300L UVC fed partly by the solar PV during the day (using an Immersun type of device) with maybe E10/E7 at night and then also the gas boiler. I would end up with two circuits – one for DHW and one for UFH. The boiler would kick in for the UFH when the UVC doesn’t require heat. BUFFER TANK? I'm also thinking that if I go for a UVC rather than thermal store (from what I have read on here) I would need a buffer store seeing I will have UFH. But I've read that if I opt for a TS, that can be my buffer tank also. So perhaps I should go for a TS rather than a UVC? Confused.... Hoping someone (AKA: @Nickfromwales etc) is able to assist..... Thanks, OB

I have been avoiding this post for a while and also been busy doing other things at the house. I need to sort out my heating design and it is proving difficult with varying opinions here in the land of the hotpress. I have a plumber who I am relatively happy with and comes highly recommended we just need to bottom out the design somewhat. Above is the floor plan and I have posted on this previously a long time ago, never thought it would take us this long to get to the point we are at. We are going to have UFH throughout along with towel rads in bathroom/en-suites, feature radiator in reception (I don't anticipate this putting much heat out) and provision for radiators in the garage. This will all be fed from an oil boiler (gas is not an option, ASHP I have ruled out and PV wont be happening). I understand that oil and UFH are not conducive for optimum performance but measures can be taken to alleviate this. The default position with almost all plumbers and heating designers here is to just feed the UFH via blending valve straight from the boiler, I hear @Nickfromwales scream what about short cycling on a boiler that cant modulate like a gas one (I have read plenty on here already). Some just don't get it is all I will say. Others agree to disagree. My options are as I see it:- Oil boiler with buffer and UVC. Question here is what size of buffer? It was suggested to me 500L but that was then going to also feed a UVC which I couldn't quite get my head around. Other option as I understand would be a 400/500L thermal store to do the lot. Any time I raise this in discussions no-one understands why I might do this if I have no wood burner etc dumping heat into it. Are there any other options? I dont really understand it all myself and my head has gone to mush with all the reading I have done. I fear my plumber may run for the hills if I dictate too much of the design to him. Please help!

Hey Googling it but can’t find it ! want a device that cuts off water flow after say 10 mins , then resets after a period of time . Trying to control how long people shower for in a rental property where I pay the bills !! cheers

So... my sparky never clocked that there are two immersions on the tank, and has decided to start again from scratch. Maybe should have had a chat about what I wanted but it looked kind of obvious to me! Setup: 170l UVC with two 3kw immersions, property is one bed, one shower, and E7 supply. Holiday let so must be idiot proof. Lower immersion will go on a timer, overnight. Upper immersion will have a simple time lag boost button set to one hour. So far so good. The overnight timer can, I think, be something very simple indeed as I don't plan to mess around with it at all. In fact I will deliberately place it out of the way to avoid people meddling with it. The boost button is a bit tricker- I ordered a cheap one that looked the biz (one big button, no meddling, no confusion). It doesn't light up or anything though. I'd also like to future proof if I can, and be able to upgrade to a 6kw boost immersion- but all the boost switches I've found are only 13A or 16A. Anybody know of a simple one-button time lag switch that can handle a 6kw resistive load? Finally, can I just place an illuminated isolator switch after the boost button? That would give a visual indicator that it had come on. Likewise can the E7 timer have the isolator between the timer and tank? That would allow me to switch it off without interupting the power to the timer itself.

@Nickfromwales Telford seem a good bet for supplying my UVC. As per other post on UFH with rads but I will now site the tank in the cellar and have an external boiler (fluing from the cellar is a pig and looks expensive). So presume new system boiler and UVC or TS. Can't invest in solar now, or air-source hp as no funds left. See system below I got quoted from Greensquare. Should I not have a buffer if going uvc?

Hi there, I'm not sure which forum to post this in, so I've taken a best guess I'll be starting large extension build next year which will involved installing a new external Oil Boiler connected to a hot water cylinder on the ground floor. unvented I believe, as there is nowhere to put a header tank? in the upstairs of the old house. The old part of the house is over two floors and will remain heated by radiators. the new extension will be underfloor heating. part of the extension is a large (to me) open plan area with a woodburner in it. now that I'm firming up the build, I'm wondering if there is any way to connect a woodburner to a cylinder, on the same floor level? Attached is a diagram of the current layout, there is hot water cylinder in a utlility room roughly 17m from the woodburner. the utility room is a single storey extension. I believe the proposed cylinder is unvented, which I guess it would need a pump to heat the radiators upstairs in the old part of the house. has anyone successfully been able to connect a woodburner/boiler stove on the same floor? .I have my doubts, but its worth a shot as I have access to an almost unlimited supply of firewood, I'd love to heat the radiators via woodburner as much as possible. I'm just in the process of engaging a builder, and would like to be able to speak to his plumber with some degree of understanding. any pointers, much appreciated.

Mostly for Nick but anyone can chip in. Our upstairs had to be re-designed on the fly as the house worked out bigger than on the plans and we were trying to make use of the space. Long story short every little move had a knock on effect, and some things got missed. SO Our hotpress is now only 850mm deep by about 2m I was hoping to get extra insulation around my tank be it UVC or TS (Nick I havent decided yet) Will i be able to get extra insulation with only 850mm to play with? Will i be able to fit any sort of tank in 850mm (will all connections be able to be fitted on one face etc?) Cheers Damian