Nickfromwales Posted February 11 Posted February 11 55 minutes ago, Mattg4321 said: I just repeated the test. Pressure measured at the kitchen sink directly off the main. New pipework so won’t be furred up etc Had the outside tap fully open. Also directly off the main. static pressure. 3.6 bar dynamic pressure. 1.4 bar with outside tap wide open flow rate at outside tap with it wide open. 18 litres per minute outside tap fed by 15mm copper not sure what that tells me! It says the supply isn’t as bad as some I’ve seen, and pressure is good, so l/p/m needs improving which should come with the new mains pipe. Will you ask for a new stopcock in the street so you’re as good as can be, or will you DIY and connect to the existing at your boundary?
Mattg4321 Posted February 11 Author Posted February 11 1 hour ago, Nickfromwales said: It says the supply isn’t as bad as some I’ve seen, and pressure is good, so l/p/m needs improving which should come with the new mains pipe. Will you ask for a new stopcock in the street so you’re as good as can be, or will you DIY and connect to the existing at your boundary? Stop cock in street looks new. Last 5-10 years. Blue pipe I seem to remember and definitely has a quarter turn handle on it. Operated by hand easily.
Nickfromwales Posted February 11 Posted February 11 6 minutes ago, Mattg4321 said: Stop cock in street looks new. Last 5-10 years. Blue pipe I seem to remember and definitely has a quarter turn handle on it. Operated by hand easily. Cool. That’s great news. Those come delivered with a short piece of 25mm MDPE either side, then the water authorities / groundwork guys subbing to them just fit a universal adapter to fit onto whatever is disappearing into your drive / garden, so you should just be able to join onto that 25mm stub by removing their adaptor and fitting a standard couple 👍👌.
John Carroll Posted February 11 Posted February 11 1 hour ago, Mattg4321 said: I just repeated the test. Pressure measured at the kitchen sink directly off the main. New pipework so won’t be furred up etc Had the outside tap fully open. Also directly off the main. static pressure. 3.6 bar dynamic pressure. 1.4 bar with outside tap wide open flow rate at outside tap with it wide open. 18 litres per minute outside tap fed by 15mm copper not sure what that tells me! The flowrate is 18.0LPM at a dP of 3.6-1.4, 2.2bar, 15M of 15mm ID pipe has a dP of 0.38bar at 18.0LPM, 15M of 11mm ID pipe has a dP of 1.72bar at 18.0LPM, so either you have a partial restriction in the (IF) 15mm piping or the ID is "only" 11mm or very close to that. Can you do that dynamic test with a hot water tap only (say the bath HOT tap) to see whats what with the UVC?. The acceptance volume is really only the (EV) airend vol/total Vol, easily determined from the precharge pressure and the final pressure, both absolute, say precharge pressure is 2.0bar = (2.0+1.0), 3.0bar.abs anf final pressure is 3.0bar =(3.0+1.0),4.0bar.abs, then the acceptance factor is (1-(3.0/4.0))*100, 25% and so on, sometime, post the UVC & the EV volumes and we can do a few calcs, I have a ancient but very easily understood spreadsheet that I built decades, will post later.
Mattg4321 Posted February 11 Author Posted February 11 (edited) 1 hour ago, John Carroll said: The flowrate is 18.0LPM at a dP of 3.6-1.4, 2.2bar, 15M of 15mm ID pipe has a dP of 0.38bar at 18.0LPM, 15M of 11mm ID pipe has a dP of 1.72bar at 18.0LPM, so either you have a partial restriction in the (IF) 15mm piping or the ID is "only" 11mm or very close to that. Can you do that dynamic test with a hot water tap only (say the bath HOT tap) to see whats what with the UVC?. The acceptance volume is really only the (EV) airend vol/total Vol, easily determined from the precharge pressure and the final pressure, both absolute, say precharge pressure is 2.0bar = (2.0+1.0), 3.0bar.abs anf final pressure is 3.0bar =(3.0+1.0),4.0bar.abs, then the acceptance factor is (1-(3.0/4.0))*100, 25% and so on, sometime, post the UVC & the EV volumes and we can do a few calcs, I have a ancient but very easily understood spreadsheet that I built decades, will post later. Looking at it properly I just measured the black alkathene main at 22mm external diameter. According to Google this could be either 15.5mm internal or 14.1 depending if Class C or D. Nominal size is 1/2 inch. This is approx 15m in length from street. Then I have approx 12m of 15mm copper pipe to position of outside tap and kitchen tap where I carried out the test. Internal diameter 13.6mm. Do you still think I have a restriction? The length in total is much further than your calcs - sorry if I provided duff info! EDIT. Also goes through a 15mm stop cock and numerous fittings - mostly copper but including 1 or 2 push fit plastic I seem to remember. Cylinder is 250 litres and the EV is 18 litres. Edited February 11 by Mattg4321
John Carroll Posted February 11 Posted February 11 OK, assume a worst case of 12.5mm ID for of 15M of pipe, this gives a dP of 0.92bar @ 18.0LPM & a dP of 0.52bar @ 18.0LPM through 12M of 13.6mm ID pipe, 0.92+0.52, 1.44bar, add 20% for fittings etc, gives a total of, 1.44*1.2, 1.73bar??
Mattg4321 Posted February 11 Author Posted February 11 16 minutes ago, John Carroll said: OK, assume a worst case of 12.5mm ID for of 15M of pipe, this gives a dP of 0.92bar @ 18.0LPM & a dP of 0.52bar @ 18.0LPM through 12M of 13.6mm ID pipe, 0.92+0.52, 1.44bar, add 20% for fittings etc, gives a total of, 1.44*1.2, 1.73bar?? Well it’s not a million miles from what I’m getting when I measure it I suppose?
John Carroll Posted February 11 Posted February 11 (edited) No, can you do the same test on the UVC only, also you wouldn't want to be setting that precharge pressure too low, you can see from the attached, (do your own calcs, never mind that acceptance factor) that the lower the precharge pressure, the higher the final pressure which may cause that noise and/ or lift the expansion relief valve, what setting is it at?, it should be either 6.0bar or maybe as high as 8.0bar, its written on the end of it. If the UVC test gave you say 16.0LPM would you be happy enough with that, apart from the noise?. Expansion Vessel Calculation Rev 0.xlsx Edited February 11 by John Carroll
Nickfromwales Posted February 11 Posted February 11 9 minutes ago, John Carroll said: what setting is it at?, it should be either 6.0bar or maybe as high as 8.0bar 6 bar on all domestic, some even 5. Defo needs pumping back up to 2.5bar pre-charge to test for 24 hrs.
Mattg4321 Posted February 11 Author Posted February 11 23 minutes ago, Nickfromwales said: 6 bar on all domestic, some even 5. Defo needs pumping back up to 2.5bar pre-charge to test for 24 hrs. Noise was much worse at 2.5 bar than at current 1.5 bar. The flow isn’t the main problem, I just want to stop the noise or mitigate it as best I can!
John Carroll Posted February 11 Posted February 11 27 minutes ago, Mattg4321 said: Noise was much worse at 2.5 bar than at current 1.5 bar. The flow isn’t the main problem, I just want to stop the noise or mitigate it as best I can! Strange allright, it seems the accumulator effect is helping even though the EV diaphragm will be moving far more at a precharge of 1.5bar vs 2.5bar. At 1.5bar precharge and after a full reheat the EV will flow 10.8L into the system with a big demand for HW and subsequently 6.75L will flow back in when the HW stops but will flow that 6.75L back out when the HW is again drawn off strongly, at 2.5bar precharge those numbers become 6.3L, and 0.9L., the only thing I can think of is that with the low precharge pressure of 1.5bar then the diaphragh will rarely if ever bottom out but will bottom out continuously with a 2.5bar precharge. Hate to be throwing new bits in the hope of fixing things but mabe a new EV plus a new PRV in case its leaking past might cure the problem but no guarantee that it will.
Mattg4321 Posted February 11 Author Posted February 11 8 minutes ago, John Carroll said: Strange allright, it seems the accumulator effect is helping even though the EV diaphragm will be moving far more at a precharge of 1.5bar vs 2.5bar. At 1.5bar precharge and after a full reheat the EV will flow 10.8L into the system with a big demand for HW and subsequently 6.75L will flow back in when the HW stops but will flow that 6.75L back out when the HW is again drawn off strongly, at 2.5bar precharge those numbers become 6.3L, and 0.9L., the only thing I can think of is that with the low precharge pressure of 1.5bar then the diaphragh will rarely if ever bottom out but will bottom out continuously with a 2.5bar precharge. Hate to be throwing new bits in the hope of fixing things but mabe a new EV plus a new PRV in case its leaking past might cure the problem but no guarantee that it will. I've tested the pressure on the balanced cold/hot at 3 bar, so that rules out PRV leaking by? Both PRV and EV only been fitted a week or so - hope they are not faulty already! Gut feeling tells me its something to do with the way its plumbed or the supply rather than faulty components
John Carroll Posted February 11 Posted February 11 17 minutes ago, Mattg4321 said: I've tested the pressure on the balanced cold/hot at 3 bar, so that rules out PRV leaking by? Both PRV and EV only been fitted a week or so - hope they are not faulty already! Gut feeling tells me its something to do with the way its plumbed or the supply rather than faulty components Is the whole installation only a week old?, what did it replace. Since the dynamic pressure is ~ 2.0bar, then maybe reduce the PRV setting to this value, there are plenty of systems I would think set up like this, where the PRV is set to or slightly above the dynamic pressure. Can you post a few photos of the system, combination valve set with PRV, expansion relief valve, balanced cold take off etc and the EV showing exactly where its teed into the combination valve set etc and pipework.
Gus Potter Posted February 12 Posted February 12 (edited) Good thread. On 10/02/2025 at 13:27, Mattg4321 said: From what I’m reading the pre charge should be 0.2 bar below the dynamic flow pressure of 0.8 bar? But you do know this varies over the day? Stop being wanky and go back to basics! Your taps and flow valves will wear over time.. I piss myself laughing at you all talking about 0.1 bar pressure, static or dynamic..oh and a couple of rough bends in the pipe and it bollocks! I can tell you that your qualitative values are complete pish in terms of long term performance. In a sealed system 0.1 bar can be lost by a mugfull of water weaping from a joint! Yes I'm the philistine.. We have been using direct cylinders for at least 30 years, well I remember it was about that long ago that I fitted one, it is not rocket science.. just needs common sense. My prediction is that your plumber will part company with you. To avoid this identify what you can live with.. start by asking the other members of you family... as good design is for all. I'll say this again. There are folk on BH that are trying to make UFH and a hot water supply into a complex subject. Yes in a big hotel say it matters a bit but for a self build.. get a grip! You are off your heads! I have been into UFH and the like long before most of you were born! @nod are we of the same age? and sometimes the elegance lies in the simplicity, low maintenance and reliability costs! I leart my skills and design skills from the Scandinavians and industrial sector, the UK self build market were late to the UFH game, ICF and insulated rafts. Funnily I was doing a lot of this stuff before the self build market got a foothold. Why! 1/ In one or two years time the valves will get sticky / pumps will wear, the boiler will wear and things will start playing up. You just can't seem to see this folks! 2/ Your average plumber will have no clue how to service all the shite you have installed. 3/ If you sell the house how on earth are you going to run this by a surveyor. I could go on. Keep it simple folks and it will save you money! Maybe test you flow rate on the incoming service pipe. Open the pipe, get a bucket and let it flow free. Time it to get the delivery of a quantity of water. Do this in the middle of the night at 4.0 am, at 7.00 am and at 4.30 pm when the kids come home from school. Do this over a couple of months or so.. the water board get leaks and muck about with the water pressure! Check between winter and summer flow delivery. Then you may realise how your calcs are a not applicable! On 10/02/2025 at 13:27, Mattg4321 said: When hot water is drawn off after it’s been heated/left for a while then we get a fairly loud gurgling noise from the expansion vessel/cylinder area. Is that it? You probaly need to fit another £ 5.00 automatic air vent from screwfix! Edited February 12 by Gus Potter
nod Posted February 12 Posted February 12 5 hours ago, Gus Potter said: Good thread. But you do know this varies over the day? Stop being wanky and go back to basics! Your taps and flow valves will wear over time.. I piss myself laughing at you all talking about 0.1 bar pressure, static or dynamic..oh and a couple of rough bends in the pipe and it bollocks! I can tell you that your qualitative values are complete pish in terms of long term performance. In a sealed system 0.1 bar can be lost by a mugfull of water weaping from a joint! Yes I'm the philistine.. We have been using direct cylinders for at least 30 years, well I remember it was about that long ago that I fitted one, it is not rocket science.. just needs common sense. My prediction is that your plumber will part company with you. To avoid this identify what you can live with.. start by asking the other members of you family... as good design is for all. I'll say this again. There are folk on BH that are trying to make UFH and a hot water supply into a complex subject. Yes in a big hotel say it matters a bit but for a self build.. get a grip! You are off your heads! I have been into UFH and the like long before most of you were born! @nod are we of the same age? and sometimes the elegance lies in the simplicity, low maintenance and reliability costs! I leart my skills and design skills from the Scandinavians and industrial sector, the UK self build market were late to the UFH game, ICF and insulated rafts. Funnily I was doing a lot of this stuff before the self build market got a foothold. Why! 1/ In one or two years time the valves will get sticky / pumps will wear, the boiler will wear and things will start playing up. You just can't seem to see this folks! 2/ Your average plumber will have no clue how to service all the shite you have installed. 3/ If you sell the house how on earth are you going to run this by a surveyor. I could go on. Keep it simple folks and it will save you money! Maybe test you flow rate on the incoming service pipe. Open the pipe, get a bucket and let it flow free. Time it to get the delivery of a quantity of water. Do this in the middle of the night at 4.0 am, at 7.00 am and at 4.30 pm when the kids come home from school. Do this over a couple of months or so.. the water board get leaks and muck about with the water pressure! Check between winter and summer flow delivery. Then you may realise how your calcs are a not applicable! Is that it? You probaly need to fit another £ 5.00 automatic air vent from screwfix! ???????
Mattg4321 Posted February 12 Author Posted February 12 5 hours ago, Gus Potter said: Good thread. But you do know this varies over the day? Stop being wanky and go back to basics! Your taps and flow valves will wear over time.. I piss myself laughing at you all talking about 0.1 bar pressure, static or dynamic..oh and a couple of rough bends in the pipe and it bollocks! I can tell you that your qualitative values are complete pish in terms of long term performance. In a sealed system 0.1 bar can be lost by a mugfull of water weaping from a joint! Yes I'm the philistine.. We have been using direct cylinders for at least 30 years, well I remember it was about that long ago that I fitted one, it is not rocket science.. just needs common sense. My prediction is that your plumber will part company with you. To avoid this identify what you can live with.. start by asking the other members of you family... as good design is for all. I'll say this again. There are folk on BH that are trying to make UFH and a hot water supply into a complex subject. Yes in a big hotel say it matters a bit but for a self build.. get a grip! You are off your heads! I have been into UFH and the like long before most of you were born! @nod are we of the same age? and sometimes the elegance lies in the simplicity, low maintenance and reliability costs! I leart my skills and design skills from the Scandinavians and industrial sector, the UK self build market were late to the UFH game, ICF and insulated rafts. Funnily I was doing a lot of this stuff before the self build market got a foothold. Why! 1/ In one or two years time the valves will get sticky / pumps will wear, the boiler will wear and things will start playing up. You just can't seem to see this folks! 2/ Your average plumber will have no clue how to service all the shite you have installed. 3/ If you sell the house how on earth are you going to run this by a surveyor. I could go on. Keep it simple folks and it will save you money! Maybe test you flow rate on the incoming service pipe. Open the pipe, get a bucket and let it flow free. Time it to get the delivery of a quantity of water. Do this in the middle of the night at 4.0 am, at 7.00 am and at 4.30 pm when the kids come home from school. Do this over a couple of months or so.. the water board get leaks and muck about with the water pressure! Check between winter and summer flow delivery. Then you may realise how your calcs are a not applicable! Is that it? You probaly need to fit another £ 5.00 automatic air vent from screwfix! Not sure that I’ve ever seen or heard of an AAV on the DHW side! Fit where exactly and how would it help?
Nickfromwales Posted February 12 Posted February 12 8 hours ago, Gus Potter said: Good thread. But you do know this varies over the day? Stop being wanky and go back to basics! Your taps and flow valves will wear over time.. I piss myself laughing at you all talking about 0.1 bar pressure, static or dynamic..oh and a couple of rough bends in the pipe and it bollocks! I can tell you that your qualitative values are complete pish in terms of long term performance. In a sealed system 0.1 bar can be lost by a mugfull of water weaping from a joint! Yes I'm the philistine.. We have been using direct cylinders for at least 30 years, well I remember it was about that long ago that I fitted one, it is not rocket science.. just needs common sense. My prediction is that your plumber will part company with you. To avoid this identify what you can live with.. start by asking the other members of you family... as good design is for all. I'll say this again. There are folk on BH that are trying to make UFH and a hot water supply into a complex subject. Yes in a big hotel say it matters a bit but for a self build.. get a grip! You are off your heads! I have been into UFH and the like long before most of you were born! @nod are we of the same age? and sometimes the elegance lies in the simplicity, low maintenance and reliability costs! I leart my skills and design skills from the Scandinavians and industrial sector, the UK self build market were late to the UFH game, ICF and insulated rafts. Funnily I was doing a lot of this stuff before the self build market got a foothold. Why! 1/ In one or two years time the valves will get sticky / pumps will wear, the boiler will wear and things will start playing up. You just can't seem to see this folks! 2/ Your average plumber will have no clue how to service all the shite you have installed. 3/ If you sell the house how on earth are you going to run this by a surveyor. I could go on. Keep it simple folks and it will save you money! Maybe test you flow rate on the incoming service pipe. Open the pipe, get a bucket and let it flow free. Time it to get the delivery of a quantity of water. Do this in the middle of the night at 4.0 am, at 7.00 am and at 4.30 pm when the kids come home from school. Do this over a couple of months or so.. the water board get leaks and muck about with the water pressure! Check between winter and summer flow delivery. Then you may realise how your calcs are a not applicable! Is that it? You probaly need to fit another £ 5.00 automatic air vent from screwfix! Jesus, lol. Did you argue with someone just before typing that? 😵💫😅. I was going to quote a few bits of it, but I’m still trying to correlate what you’ve said vs relevance to this thread….. Its not complicated, its a bog-standard UVC conversion with one teething issue. 🤷♂️. Servicing UVC’s is basic G3 stuff. So, do you need a cuddle or what? 1
Mattg4321 Posted February 12 Author Posted February 12 2 hours ago, John Carroll said: Is your system plumbed up like this?. Yes although EV from pipework to cylinder. Which looks fine from my research.
John Carroll Posted February 12 Posted February 12 Is the EV just teed in somewhere down stream of the valve set on the cold supply to the cylinder?
Nickfromwales Posted February 12 Posted February 12 2 hours ago, John Carroll said: Is the EV just teed in somewhere down stream of the valve set on the cold supply to the cylinder? Ah! It’s a dark pic, but I think the issue is that the EV has mistakenly been teed off before the PRedV / control group. @Mattg4321, can you take a better pic or confirm if that’s the case? If so, then we’ve got the answer methinks. The EV should be tapped in by removing the black plastic plug on the rear of the control group, ideally.
Mattg4321 Posted February 12 Author Posted February 12 2 hours ago, John Carroll said: Is the EV just teed in somewhere down stream of the valve set on the cold supply to the cylinder? Yes
Nickfromwales Posted February 12 Posted February 12 2 hours ago, John Carroll said: Is the EV just teed in somewhere down stream of the valve set on the cold supply to the cylinder? Upstream, not downstream
John Carroll Posted February 12 Posted February 12 To avoid any confusion, it should be teed in somewhere between the valve set and the UVC cold water inlet, I call(ed) this downstream, which I think @Mattg4321 has confirmed, in other words, correctly, whatever about ideally.
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