Nickfromwales Posted December 31, 2018 Share Posted December 31, 2018 2 hours ago, Nelliekins said: Hmmm you have got me wondering now! There is definitely 2 for coil, 2 on opposite side (top and bottom) and vent out at top. Be good if you have as you'll have a separate flow tapping for the DHW PHE. With regards to sustain, I wouldn't worry about sapping the cylinder as the space heating wont even blink if its has an empty buffer for 30 mins or so. Only issue will be the useful temp cut-off point of ~40oC but if you set the cylinder set temp to ~65oC and try it I think you'll be fine. If your DHW usage is higher and you find yourself needing more 'capacity', just incrementally raise the set temp by 2oC and retry daily, adjusting accordingly as you go, until your happy. Link to comment Share on other sites More sharing options...
Nelliekins Posted December 31, 2018 Author Share Posted December 31, 2018 1 hour ago, Nickfromwales said: Be good if you have as you'll have a separate flow tapping for the DHW PHE. With regards to sustain, I wouldn't worry about sapping the cylinder as the space heating wont even blink if its has an empty buffer for 30 mins or so. Only issue will be the useful temp cut-off point of ~40oC but if you set the cylinder set temp to ~65oC and try it I think you'll be fine. If your DHW usage is higher and you find yourself needing more 'capacity', just incrementally raise the set temp by 2oC and retry daily, adjusting accordingly as you go, until your happy. I assumed the PHE flow would tee off the vent connection right at the top of the cylinder, next to the immersion port. The boiler would connect to the direct ports (top and bottom) on the opposite side of the tank to the coil ports. So would I tee the PHE return with the boiler return, or add a new flanged fitting at the bottom for the PHE return? Do you agree with @PeterW that the UFH buffer is probably not needed, and I can simply heat via the coil? Or am I better with a separate buffer tank, if only so I can use another immersion to assist with initial heating of the UFH? Link to comment Share on other sites More sharing options...
newhome Posted December 31, 2018 Share Posted December 31, 2018 3 hours ago, Nickfromwales said: Just enough time to try all your frocks on Images I cannot un-see Aw, I bet he looked cute ? with the stilettos ? on ?. 1 Link to comment Share on other sites More sharing options...
Jeremy Harris Posted December 31, 2018 Share Posted December 31, 2018 9 hours ago, PeterW said: You cannot wire the pump direct to the switch ..! Have to put a relay in as otherwise you will fry the contacts, irrespective of what the MIs say about current rating ..! If you get the flow switch I used to circulate water through our PHE, then you can wire it direct to the pump, as it has a built in triac that can switch 3 amps: https://cpc.farnell.com/gentech-international/fs-01/flow-switch-noryl-ac/dp/SN36161 1 Link to comment Share on other sites More sharing options...
PeterW Posted December 31, 2018 Share Posted December 31, 2018 15 minutes ago, JSHarris said: If you get the flow switch I used to circulate water through our PHE, then you can wire it direct to the pump, as it has a built in triac that can switch 3 amps: https://cpc.farnell.com/gentech-international/fs-01/flow-switch-noryl-ac/dp/SN36161 Thanks @JSHarris - I was referring to the one that @Nelliekins linked as that was the one we had issues with. Useful to know that there is one with a decent current control. Link to comment Share on other sites More sharing options...
PeterW Posted December 31, 2018 Share Posted December 31, 2018 4 hours ago, newhome said: Aw, I bet he looked cute ? with the stilettos ? on ?. You don't want to know what @Nickfromwales was doing .... ?? ? 2 Link to comment Share on other sites More sharing options...
Nelliekins Posted December 31, 2018 Author Share Posted December 31, 2018 (edited) 1 hour ago, JSHarris said: If you get the flow switch I used to circulate water through our PHE, then you can wire it direct to the pump, as it has a built in triac that can switch 3 amps: https://cpc.farnell.com/gentech-international/fs-01/flow-switch-noryl-ac/dp/SN36161 Thanks, @JSHarris - ordered! Any recommendations on pumps - I see Wilo and Grundfos being used in most places, and wouldn't know how to choose between them. Is one brand longer lasting (ie higher MTBF)? Or quieter, I guess that might be nice? Or failing that, cheaper? ? @PeterW and @Nickfromwales - one of you clearly needs to make the first move here. Be brave - BH is here for you! ??❤️???? Edited December 31, 2018 by Nelliekins Auto correct corrections 1 Link to comment Share on other sites More sharing options...
ProDave Posted December 31, 2018 Share Posted December 31, 2018 Wilo and Grundfoss are both recommended as they are reliable and quiet. My UFH manifolds came with IBO pumps. Horrible noisy things. I have changed one for a Wilo already and still have to get around to changing the other one. The last thing you want with a heating system is a horrible droning whine all the time. 1 Link to comment Share on other sites More sharing options...
Jeremy Harris Posted December 31, 2018 Share Posted December 31, 2018 Wilo seem to be slightly quieter than Grundfos, based on our experience, although both are pretty quiet. We have a Grundfos pump on the UFH manifold and a Wilo on the DHW preheat PHE circuit and the Wilo is definitely quieter, so much so that I've had to fit a light to show that the flow switch has turned the pump on, as I can't hear it running. 1 Link to comment Share on other sites More sharing options...
PeterW Posted December 31, 2018 Share Posted December 31, 2018 Can’t beat these Wilo Pico pumps for performance - virtually silent too. Best price seems to be Screwfix too 1 Link to comment Share on other sites More sharing options...
Nelliekins Posted December 31, 2018 Author Share Posted December 31, 2018 14 minutes ago, PeterW said: Can’t beat these Wilo Pico pumps for performance - virtually silent too. Best price seems to be Screwfix too Thanks @PeterW. I presume I should put a set of gate valves either side of them, to make eventual replacement easier? Link to comment Share on other sites More sharing options...
PeterW Posted December 31, 2018 Share Posted December 31, 2018 Yes you need pump valves either end. I would use Pegler ones. I also think this PHE and pump need to go across the tank input and output, not across the vent pipe and output. Reason being, the PHE and DHW need priority and tbh the tank won’t stratify as it’s too small - if you use the vent pipe, there is a chance that the PHE pump will just pull the tank content rather than take the full heat of the boiler which may result in lukewarm water. 1 Link to comment Share on other sites More sharing options...
Nickfromwales Posted December 31, 2018 Share Posted December 31, 2018 1 hour ago, PeterW said: Yes you need pump valves either end. I would use Pegler ones. I also think this PHE and pump need to go across the tank input and output, not across the vent pipe and output. Reason being, the PHE and DHW need priority and tbh the tank won’t stratify as it’s too small - if you use the vent pipe, there is a chance that the PHE pump will just pull the tank content rather than take the full heat of the boiler which may result in lukewarm water. Yup. 9 hours ago, Nelliekins said: so I can use another immersion to assist with initial heating of the UFH? Definitely a waste of time and money. Your boiler will be chucking 30kW in and another immersion would only provide another 3, totally pointless. 9 hours ago, Nelliekins said: Do you agree with @PeterW that the UFH buffer is probably not needed, and I can simply heat via the coil? 100%, dress or no dress. Link to comment Share on other sites More sharing options...
Nickfromwales Posted December 31, 2018 Share Posted December 31, 2018 @PeterW Any benefit from going out the top via a Sussex? It’ll be the hottest water after all. I’d be happy enough as long as the cyl stat is kept ( mounted ) low tbh. Link to comment Share on other sites More sharing options...
Nelliekins Posted December 31, 2018 Author Share Posted December 31, 2018 1 hour ago, PeterW said: Yes you need pump valves either end. I would use Pegler ones. I also think this PHE and pump need to go across the tank input and output, not across the vent pipe and output. Reason being, the PHE and DHW need priority and tbh the tank won’t stratify as it’s too small - if you use the vent pipe, there is a chance that the PHE pump will just pull the tank content rather than take the full heat of the boiler which may result in lukewarm water. OK, leave the vent as a vent, got it. So would you suggest tee off both top and bottom (1 pair for boiler, 1 pair for PHE)? Or fit new flanges for the PHE? Link to comment Share on other sites More sharing options...
PeterW Posted December 31, 2018 Share Posted December 31, 2018 1 hour ago, Nickfromwales said: @PeterW Any benefit from going out the top via a Sussex? It’ll be the hottest water after all. I’d be happy enough as long as the cyl stat is kept ( mounted ) low tbh. Be about 15 usable litres above it - can’t see the point tbh. It’s purely as a buffer to stop the boiler firing every time it needs a bowl of water or someone washes their hands. When the showers kick in, you’ve probably got about 3-4 mins before the boiler kicks in and takes over providing heat to the PHE. I’d mount the stat about 6” above the bottom inlet directly opposite the outlet. It will probably be mid point of the coils for the UFH at that point too. 1 hour ago, Nelliekins said: OK, leave the vent as a vent, got it. So would you suggest tee off both top and bottom (1 pair for boiler, 1 pair for PHE)? Or fit new flanges for the PHE? Top inlet I would use a tee upright, boiler into the top, tee to the tank and bottom to the PHE. Bottom I would use tee horizontal with left to boiler return, top to PHE and right to tank. Pump below the PHE pumping downwards, maximize any convection through it. 1 Link to comment Share on other sites More sharing options...
Nelliekins Posted December 31, 2018 Author Share Posted December 31, 2018 2 hours ago, PeterW said: Be about 15 usable litres above it - can’t see the point tbh. It’s purely as a buffer to stop the boiler firing every time it needs a bowl of water or someone washes their hands. When the showers kick in, you’ve probably got about 3-4 mins before the boiler kicks in and takes over providing heat to the PHE. I’d mount the stat about 6” above the bottom inlet directly opposite the outlet. It will probably be mid point of the coils for the UFH at that point too. Top inlet I would use a tee upright, boiler into the top, tee to the tank and bottom to the PHE. Bottom I would use tee horizontal with left to boiler return, top to PHE and right to tank. Pump below the PHE pumping downwards, maximize any convection through it. That's fantastic, thanks @PeterW. Even a pillock like me can follow those instructions! ? Better head to screwfix tomorrow then! Link to comment Share on other sites More sharing options...
Nickfromwales Posted December 31, 2018 Share Posted December 31, 2018 4 hours ago, Nelliekins said: Better head to screwfix tomorrow then! Best of British with that lol. 1 Link to comment Share on other sites More sharing options...
PeterW Posted January 1, 2019 Share Posted January 1, 2019 17 hours ago, Nelliekins said: That's fantastic, thanks @PeterW. Even a pillock like me can follow those instructions! ? Better head to screwfix tomorrow then! So as they are all closed today... are you making a list ..?? Assuming the PHE has threaded connections ..? Tank got 22mm compression ..? Are you doing this in copper and compression or push fit..? Link to comment Share on other sites More sharing options...
Nelliekins Posted January 1, 2019 Author Share Posted January 1, 2019 13 hours ago, PeterW said: So as they are all closed today... are you making a list ..?? Assuming the PHE has threaded connections ..? Tank got 22mm compression ..? Are you doing this in copper and compression or push fit..? Sorry @PeterW I was at site all day, mainly fitting the UFH loop into the main bathroom, now that Kim has picked a bath at long last. I really don't like the stiff PEX pipe... Should have researched that more before I bought! I am thinking of a mix tbh, with everything connected to boiler or tank in copper + compression, and everything else (eg the hot/cold/RWH manifolds) in push fit. The manifolds are being sited in the laundry alongside the upstairs UFH manifold and the tank, so central isolation of every outlet instead of individual stop taps everywhere... Allows me to commission stuff in stages, and simplify the "RWH backup from mains" side of things. I have about a dozen 22mm push fit elbows and half that number of Tee fittings. I also have a bag full of 15mm & 22mm compression fittings of various types. I tend to prefer push fit if it's all going to be serviceable / accessible, and solder or compression if not... Had 10 out of 12 Floplast push fit 15mm elbows leak in the first 2 weeks, replaced most with Speedfit fittings and a couple with compression and not so much as a drip in the 5 weeks since. Lesson learnt - you get what you pay for. Anyone know of a reason not to use 16mm PEX pipe for hot/cold/RWH feeds around the house? The fittings are only a couple of quid each to convert to 15mm COMPRESSION, and the PEX pipe has WRAS approval, and is good for upto 95C, and I have about 600m of the pipe left over from doing the UFH ? Link to comment Share on other sites More sharing options...
Nelliekins Posted January 1, 2019 Author Share Posted January 1, 2019 14 hours ago, PeterW said: Assuming the PHE has threaded connections ..? Tank got 22mm compression ..? Sorry missed this. Yes to both. PHE is 1" BSPP and tank is all 22mm compression - they even supplied the olives! ? Link to comment Share on other sites More sharing options...
Nickfromwales Posted January 2, 2019 Share Posted January 2, 2019 20 minutes ago, Nelliekins said: Anyone know of a reason not to use 16mm PEX pipe for hot/cold/RWH feeds around the house? The fittings are only a couple of quid each to convert to 15mm COMPRESSION, and the PEX pipe has WRAS approval, and is good for upto 95C, and I have about 600m of the pipe left over from doing the UFH No reason not too at all, other than converting to 15mm. Done it a few times where the pipe was over-ordered. 1 Link to comment Share on other sites More sharing options...
PeterW Posted January 2, 2019 Share Posted January 2, 2019 PEX as water pipes is fine but also invest in some blue and red insulation tape and mark all the pipes as you go. 1 Link to comment Share on other sites More sharing options...
PeterW Posted January 2, 2019 Share Posted January 2, 2019 Oh yeh - buy Hep2O next time too... ? Floplast push fits are made from recycled pot noodle tubs.... 1 1 Link to comment Share on other sites More sharing options...
Nelliekins Posted January 2, 2019 Author Share Posted January 2, 2019 8 hours ago, PeterW said: Oh yeh - buy Hep2O next time too... ? Floplast push fits are made from recycled pot noodle tubs.... The manifolds for hot /cold /RWH will be the Hep2O sectional units that screw together, so that I could get both 15mm and 22mm feeds off the same 3/4" input pipe. That said I do prefer Speedfit for elbows etc - no idea why but the twist lock seems to give me some comfort, and they've never let me down yet. 8 hours ago, PeterW said: PEX as water pipes is fine but also invest in some blue and red insulation tape and mark all the pipes as you go. And black/green stripy, since we are doing RWH as well! ? Link to comment Share on other sites More sharing options...
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