Spinny Posted February 23 Share Posted February 23 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. Link to comment Share on other sites More sharing options...
Spinny Posted February 23 Author Share Posted February 23 PS I have recently been made aware that MLC pipe is not necessarily what it might seem. That is: 16mm MLC is only 12mm internal bore, but worse every crimped join restricts bore further (suppliers brochures don’t seem to say ?!?) but 10mm ? 9mm ? Likewise even 25mm MLC is 20mm internal bore but restricted to what at crimped joins 18mm ? 17mm ? Link to comment Share on other sites More sharing options...
Spinny Posted February 23 Author Share Posted February 23 PS I have recently been made aware that MLC pipe is not necessarily what it might seem. That is: 16mm MLC is only 12mm internal bore, but worse every crimped join restricts bore further (suppliers brochures don’t seem to say ?!?) but 10mm ? 9mm ? Likewise even 25mm MLC is 20mm internal bore but restricted to what at crimped joins 18mm ? 17mm ? Link to comment Share on other sites More sharing options...
ProDave Posted February 24 Share Posted February 24 The lack of tundish and discharge pipework is serious. Has the installer signed this off as it is non compliant. Get them back to correct this. What on earth is that rats nest of wiring in the bottom, did they do that? It sounds like your mains supply cannot support much flow. You will be lucky to get 2 simultaneous showers from that. Perhaps a mains accumulator would solve that? 1 Link to comment Share on other sites More sharing options...
JohnMo Posted February 24 Share Posted February 24 12 hours ago, Spinny said: 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 ?! On both counts - This is not compliant the manufacturer instructions for the UVC and not compliant with G3 regulations. Is he certified to install and certify, ask him for his certificate and then report him to the certifying body (that will be on his certificate card that he is obliged to show you). Your installer is supposed to do static and dynamic pressure tests, it has to meet a minimum threshold for both to allow an UVC install to go ahead as a suitable solution. Not sure I would trust that fitting copper to lead either. This is how your cylinder should be configured. You have should have two pipes going to either individual or one combined tundish one from the combined valve and one from over pressure relief. Other comments the vertical pipe from the top of the cylinder will leach heat away from the cylinder at a high rate. To fix this do a 90 Deg at the cylinder connector, come the cylinder edge and the go down a min of 150mm the go back up. This is called a heat trap. 1 Link to comment Share on other sites More sharing options...
Spinny Posted February 24 Author Share Posted February 24 Wow, thank you. Plumber is gas safe registered - not sure if you can check G3? presumably a Ton Dish something like red lines on this photo then ? Presume it can be made to discharge into same drainage outlet as boiler condensate ? The wiring is temporary, sparky still to tidy up/complete moving onto new circuit. Got two Heatmiser wiring hubs, manifolds & Pumps down there. One heating a concrete slab, t’other omnie u/floor heating. lead to copper join photo attached. This join has not been changed so is at least 30 years old. I am currently trying to get quotes to mole in a new 32mm MDPE mains pipe. (If you can suggest any contractors for moling in the Bristol area I would be grateful.) is there a way I can check the dynamic pressure on the outside tap ? Link to comment Share on other sites More sharing options...
JohnMo Posted February 24 Share Posted February 24 You can check on any tap. Static is the pressure with no taps open, you then open a tap and the resulting pressure is the dynamic pressure. 1 Link to comment Share on other sites More sharing options...
JohnMo Posted February 24 Share Posted February 24 Tundish as per photo. There are requirements for sizes and bend positions. 1 Link to comment Share on other sites More sharing options...
Conor Posted February 24 Share Posted February 24 The 15mm pipework and stop tap on the incoming supply will be a bit of a bottleneck. I'd replace the old lead pipe, probably encrusted and causing a fair bit of friction. Check your water suppliers policy, it should be free on the site if you replace yours ast far as the boundary. 1 Link to comment Share on other sites More sharing options...
Spinny Posted February 24 Author Share Posted February 24 Thank you. I have just found the cylinder design & install instructions for the gledhill cylinder online. It seems the cylinder is supplied with a tun dish - so wonder where it is ? I see the discharge pipework has to be metal (presumably copper?) so the plastic waste pipe presumably isn’t going to be good enough. Very worried now on a number of fronts. It may be that some u/floor heating will have to be taken up for access. why aren’t some gas safe people apparently either competent or trustworthy ? Sigh. Link to comment Share on other sites More sharing options...
Spinny Posted February 24 Author Share Posted February 24 Can anyone comment on the use of MLC pipe and tell me what bore they are restricted down to at the crimped connectors ? (The mains pipe needs sorting, but connecting a new one onto the 25mm MLC which is effectively perhaps only 17mm internal diameter seems a bad idea. As is 16mm MLC with an effective bore of 10mm going to kitchen taps etc.) Link to comment Share on other sites More sharing options...
Spinny Posted February 24 Author Share Posted February 24 Another pic showing stop tap & water softener pipework. Link to comment Share on other sites More sharing options...
Mr Punter Posted February 24 Share Posted February 24 1 hour ago, Spinny said: I am currently trying to get quotes to mole in a new 32mm MDPE mains pipe. Interesting. Try contacting the water supplier. I have a property in Hove and Southern Water are replacing the lead supply pipe F.O.C. as part of a scheme. I think they do up to 12m. 1 Link to comment Share on other sites More sharing options...
Spinny Posted February 24 Author Share Posted February 24 Thanks I tried the water company, but they will only do short runs and mine is 22m from pavement stop tap to house stop tap. So I am going to have to pay and contract someone myself.🙄 Link to comment Share on other sites More sharing options...
Spinny Posted February 24 Author Share Posted February 24 Just made some dynamic pressure measurements… Static Pressure on 15mm outside tap coming off nr the mains stop cock is 3.4Bar if I put the outside tap full on (20l/m) and take pressure at 15mm toilet cistern connected to the same 15mm pipe branch the pressure falls to only around 1 bar. Pressure at outside tap when running upstairs taps is… 1 cold tap on = 2.4Bar 2 cold taps on = 1.7Bar 2 cold & 2 hot taps on = 1 Bar Q1 So I guess the issue is fairly major dynamic pressure drop from current lead mains feed? Q2 If I get say a 32mm MDPE pipe put in will I get less pressure drop for a given dynamic flow ? Q3 Any way to estimate it ? Q4 Is the 22m distance from the mains a significant issue and would some other type of low friction pipe be better than MDPE ? Q5 Do water companies limit the size of the pipe connection you are allowed to have to the mains ? (Will they not connect 32mm, or effectively choke it down through a 25mm connector ?) Q6 Does type of stopcock make an appreciable difference ? (My current stop cock tends to start drip leaking if you try to open it too far.) Sorry, too many questions. Thank you for any and all help you can give. Been fighting endless issues since my builder started a one storey extension 1.5 YEARS ago! Link to comment Share on other sites More sharing options...
JohnMo Posted February 24 Share Posted February 24 Your manual will say something like the below service pipe into the dwelling should be a minimum of 22mm (usually in the form of a 25mm MDPE supply). The optimum performance is achieved if the inlet pressure is 3 bar dynamic. However, will function with lower inlet pressures, but this will reduce the performance. There should be a flow of at least 30 litres per minute or above available into the property. Normally Ideal HP provides well in excess of 40 litres/min in most conditions. Q4, 22m isn't a long way, 25mm will.be fine. Lower friction, already a smooth surface, no need to look elsewhere. Q5 yes and you don't need 32mm. Q6 yes if it's part open. It should be fully open - if the leak is from the stem tighten the nut where the valve stem comes out the body, to punch the gland a little tighter. 1 Link to comment Share on other sites More sharing options...
Spinny Posted February 25 Author Share Posted February 25 So can someone comment on the effects of MLC pipe crimped connectors and the reduced pipe bore. As well as the reduced bore (what is it reduced to ?) someone has pointed out the Venturi effect whereby the downstream pressure is reduced by introducing a constriction e.g. see image. Seems to me using MLC pipe with crimped pinch points is a bad idea. Not much point connecting a new 25mm MDPE mains pipe with 20mm bore to a 25mm MLC pipe with perhaps only 17mm bore at every crimped connection ? Also would it be better to be using a manifold approach rather than just teeing off tap connections along a pipe ? Seems to be a lot more to effectively piping a UVC system than one might think. Link to comment Share on other sites More sharing options...
Spinny Posted March 3 Author Share Posted March 3 Still seeking lead pipe replacement quotes. One suggested I should get in excess of 30l/m if it is done. Have checked the stop tap in the pavement and found that is lead too. So I seem to have lead pipe all the way past the pavement stopgap and on to the main itself. They updated the main about 15 years ago but seem to have left lead service pipes to the stop tap. How mad is that - they must have done half a job. Waiting for someone from the water company to come out and look now. Link to comment Share on other sites More sharing options...
Spinny Posted March 3 Author Share Posted March 3 Link to comment Share on other sites More sharing options...
Spinny Posted March 3 Author Share Posted March 3 PS Can anyone tell me the inner bore of MLC pipe crimp connectors ? (or is it an industry secret ?🫣) Link to comment Share on other sites More sharing options...
JohnMo Posted March 3 Share Posted March 3 23 minutes ago, Spinny said: PS Can anyone tell me the inner bore of MLC pipe crimp connectors ? (or is it an industry secret ?🫣) I would expect it's a secret. Localised reduced bore has little real effect on system pressure drops, if you do the pressure loss calcs. Would think there will be a pressure drop table in the install manual, just a matter of finding it online. Link to comment Share on other sites More sharing options...
John Carroll Posted March 10 Share Posted March 10 (edited) On 24/02/2024 at 15:02, Spinny said: Just made some dynamic pressure measurements… Static Pressure on 15mm outside tap coming off nr the mains stop cock is 3.4Bar if I put the outside tap full on (20l/m) and take pressure at 15mm toilet cistern connected to the same 15mm pipe branch the pressure falls to only around 1 bar. Pressure at outside tap when running upstairs taps is… 1 cold tap on = 2.4Bar 2 cold taps on = 1.7Bar 2 cold & 2 hot taps on = 1 Bar Q1 So I guess the issue is fairly major dynamic pressure drop from current lead mains feed? Q2 If I get say a 32mm MDPE pipe put in will I get less pressure drop for a given dynamic flow ? Q3 Any way to estimate it ? See link which gives the pressure loss for HDPE which I presume will be similar to MDPE. Using that link it seems that the ID of the existing 22M length is ~ 10mm ID based on your flowrates. Assuming a flow rate of 25LPM is adequate?, then If you use 32mm MDPE which has a ID of 26mm the pressure loss is only 0.06bar which leaves a dynamic pressure of 3.3M, if you use 25mm MDPE with 20mm ID the pressure loss is still only 0.22 bar which still leaves alnost 3.2M dynamic, you can't do much better than that (because you can't do anything about the static pressure) regarding that 22M length of piping. https://www.nationalpump.com.au/calculators/friction-loss-calculator/ Q4 Is the 22m distance from the mains a significant issue and would some other type of low friction pipe be better than MDPE ? Q5 Do water companies limit the size of the pipe connection you are allowed to have to the mains ? (Will they not connect 32mm, or effectively choke it down through a 25mm connector ?) Q6 Does type of stopcock make an appreciable difference ? (My current stop cock tends to start drip leaking if you try to open it too far.) Sorry, too many questions. Thank you for any and all help you can give. Been fighting endless issues since my builder started a one storey extension 1.5 YEARS ago! Edited March 10 by John Carroll Link to comment Share on other sites More sharing options...
Spinny Posted March 20 Author Share Posted March 20 Please can someone confirm arrangements re plumber photo id etc… Plumber has a Gas Safe photo ID card. Should he have a separate photo ID card for G3 certification ? Or should G3 certification be recorded on the Gas Safe Card itself ? (Plumber is claiming he has done G3 but not yet recorded on his gas safe card ? How do I check this ?) Link to comment Share on other sites More sharing options...
Spinny Posted March 30 Author Share Posted March 30 This is what the plumber has done to install the tundish he had failed to install below. Does this meet regs ? Link to comment Share on other sites More sharing options...
Spinny Posted March 30 Author Share Posted March 30 Link to comment Share on other sites More sharing options...
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