Gav_P Posted November 16, 2018 Share Posted November 16, 2018 Simple question that I couldn’t find an answer for when googling... How far from an Unvented Cylinder can you put an expansion vessel? The reason for asking it to simplify access for annual testing. My UVC is a horizontal cylinder in a small loft space and you have to mimic a catapillar to get alongside it. I’d like to place the the vessel near the loft hatch (2metre approx from the point it currently is). Link to comment Share on other sites More sharing options...
Temp Posted November 16, 2018 Share Posted November 16, 2018 I believe the expansion vessel can go anywhere on the sealed loop that it's protecting. So could even be on a different floor. Some may have to be in the right orientation? 1 Link to comment Share on other sites More sharing options...
Gav_P Posted November 16, 2018 Author Share Posted November 16, 2018 Thanks @Temp , so if that’s the case, I just add a couple of metres of pipe from the existing take off point. Simples. Link to comment Share on other sites More sharing options...
ProDave Posted November 16, 2018 Share Posted November 16, 2018 Regardless of where the expansion vessel is, they will also need access to the input group and the pressure releif valve. 1 Link to comment Share on other sites More sharing options...
Gav_P Posted November 17, 2018 Author Share Posted November 17, 2018 The PRV is accessable. It’s just there is virtually no space to get at the vessel, never mind get anything on it to pressure check it. What’s ‘the input group’? Link to comment Share on other sites More sharing options...
Nickfromwales Posted November 17, 2018 Share Posted November 17, 2018 The inlet or control group is the multifunction valve that has the 3bar PRedV, the balanced cold draw off point ( where ALL cold feeds for mixer outlets must originate from without exception ( however there is a compliant work-around if it’s a retrofit so ask if you need more info )) and must be within 500mm of the UVC. You can bend that rule a bit, say to locate the group at the attic hatch end of the UVC, but keep it as close as possible. The EV question is easy, carry on with what you want. The absolute rule is no valves / anything between the EV connection point and the EV other than a lockable service valve. Link I routinely fit these as it makes the annual inspection SO much quicker and easier, but good observation of local isolation and some drain points make this unnecessary. Is this a new install ? Have the balanced cold feeds been done from the control group? 1 1 Link to comment Share on other sites More sharing options...
ProDave Posted November 17, 2018 Share Posted November 17, 2018 The input group is what the cold water into the cylinder passes through. It has a pressure reducing valve, typical pre set to 3 bar, and an over pressure relief valve. This is installed by the plumber usually close to the tank. The tank itself has an over temp /pressure relief valve usually connected directly to the tank by the manufacturer. This one cannot be remote mounted it has to stay on the tank. Both need to be accessible. 1 Link to comment Share on other sites More sharing options...
Gav_P Posted November 17, 2018 Author Share Posted November 17, 2018 @Nickfromwales & @ProDave ah I understand. In that case, yes it has the input group with the balanced cold feed to the rest of the house (except outside tap). It is is a new (middle of last year) install, done as part of my building works. But access was very different at the time as no plasterboarding has been some. The PRV on the cylinder was the one I mentioned above and that is accessable enough to test. The PRV on the input group is a bugger to get at, but is currently about 250mm from the UVC. Moving this to somewhere more useful would put it about 1500mm away from the cylinder, so a bit of a no go. I think I’ll just move the EV and add one of those lockable service valves recommended by Nick. Thanks Chaps Link to comment Share on other sites More sharing options...
Nickfromwales Posted November 17, 2018 Share Posted November 17, 2018 Don’t forget to do your annual inspection and get the benchmark book stamped to keep your warranty in check 1 Link to comment Share on other sites More sharing options...
Gav_P Posted December 26, 2020 Author Share Posted December 26, 2020 On 17/11/2018 at 14:24, Nickfromwales said: Don’t forget to do your annual inspection and get the benchmark book stamped to keep your warranty in check 2 years on and I’ve eventually ordered the bits to move the EV. This was only because water was splashing out of the tundish (cheap small one fitted) and dripping into the room below... possibly due to me not having the annual inspection and the EV has lost pressure ? 1 Link to comment Share on other sites More sharing options...
ProDave Posted December 27, 2020 Share Posted December 27, 2020 9 hours ago, Gav_P said: 2 years on and I’ve eventually ordered the bits to move the EV. This was only because water was splashing out of the tundish (cheap small one fitted) and dripping into the room below... possibly due to me not having the annual inspection and the EV has lost pressure ? If water is regularly coming out of the tundish, you have a problem. The "solution" is not to change the tundish, but find and fix the problem. Most likely related to the EV. 1 Link to comment Share on other sites More sharing options...
Gav_P Posted December 27, 2020 Author Share Posted December 27, 2020 45 minutes ago, ProDave said: If water is regularly coming out of the tundish, you have a problem. The "solution" is not to change the tundish, but find and fix the problem. Most likely related to the EV. Yeah, it’s only coming out at night time when the cylinder is heated by economy7 powered immersion. So I’m fairly certain it’s the EV - which I am sorting out today (the tundish I will just replace as a consequence of the splashing, not as a fix to the venting). Link to comment Share on other sites More sharing options...
Nickfromwales Posted December 27, 2020 Share Posted December 27, 2020 You need at least 300mm of vertical pipe above the tundish to have the water come out ‘straight’ eg without ‘turbulence’, which is usually the main cause of water splashing out / over the tundish. Don’t forget to ream the pipe internally to remove the cup end, formed by rotary pipe cutters. Even though you can get away with the factory supplied 15mm in > 22mm out jobby I alswsus upgrade to a 22mm in > 22 or 28mm out to alleviate any such issues 1 Link to comment Share on other sites More sharing options...
Gav_P Posted December 27, 2020 Author Share Posted December 27, 2020 4 minutes ago, Nickfromwales said: You need at least 300mm of vertical pipe above the tundish to have the water come out ‘straight’ eg without ‘turbulence’, which is usually the main cause of water splashing out / over the tundish. Don’t forget to ream the pipe internally to remove the cup end, formed by rotary pipe cutters. Even though you can get away with the factory supplied 15mm in > 22mm out jobby I alswsus upgrade to a 22mm in > 22 or 28mm out to alleviate any such issues So ideally it needs at least 600mm of straight in total? This extra 300 above plus the reg 300 below? I have actually ordered a 22mm to 32mm Hotun as it’s discharging into a soil stack. I’m gonna get rid of the existing fanny trap too, as the Hotun is supposedly a trap too. Link to comment Share on other sites More sharing options...
Gav_P Posted December 27, 2020 Author Share Posted December 27, 2020 Also, does anyone know if you can clip pipes to the cylinder? similar to the way pre-plumbed cylinders have pipes secured to them. Link to comment Share on other sites More sharing options...
PeterW Posted December 27, 2020 Share Posted December 27, 2020 14 minutes ago, Gav_P said: Also, does anyone know if you can clip pipes to the cylinder? similar to the way pre-plumbed cylinders have pipes secured to them. Yes - use 1” stainless self tappers. 1 Link to comment Share on other sites More sharing options...
Gav_P Posted December 27, 2020 Author Share Posted December 27, 2020 Out of interest, could anyone educate me as to why the expansion vessel is located on the cold feed pipe between the input group and the cylinder and not from the cylinder directly? For example I have a spare inlet for the Secondary Return. Could the EV be connected there instead? Would there be any difference in how it performs its task or is it something to do with protecting the cold feed? Link to comment Share on other sites More sharing options...
PeterW Posted December 27, 2020 Share Posted December 27, 2020 Bladders last longer with cold water - don’t get as much degradation of the EDPM as you would with water at 55-70°C. 1 Link to comment Share on other sites More sharing options...
Gav_P Posted February 15, 2021 Author Share Posted February 15, 2021 (edited) I’ve got a duff immersion thermostat on my UVC. Just ordered a replacement, but it got me thinking about which immersion should be the primary. Normally it’s obvious in a vertical cylinder (lower one for whole tank heating, upper one for quick / small amount of hot water)... but I’ve no idea on a horizontal cylinder. Any suggestions? Here is a picture of it with locations (end and middle): Edited February 15, 2021 by Gav_P Link to comment Share on other sites More sharing options...
PeterW Posted February 15, 2021 Share Posted February 15, 2021 Which is the water out..?? Link to comment Share on other sites More sharing options...
Gav_P Posted February 15, 2021 Author Share Posted February 15, 2021 12 minutes ago, PeterW said: Which is the water out..?? Funnily enough the diagram doesn’t show it. It’s actually where the PRV is (and the PRV is nearer the middle), so straight out the top above the coil. Link to comment Share on other sites More sharing options...
PeterW Posted February 15, 2021 Share Posted February 15, 2021 I’d have the boost one as the one through the coil then. What length is the immersion ..? 1 Link to comment Share on other sites More sharing options...
Nickfromwales Posted February 15, 2021 Share Posted February 15, 2021 (edited) On 27/12/2020 at 18:09, PeterW said: Bladders last longer with cold water - don’t get as much degradation of the EDPM as you would with water at 55-70°C. Plus you don't want an incidental 'warm radiator' instead of a cold EV Edited February 15, 2021 by Nickfromwales 1 Link to comment Share on other sites More sharing options...
Nickfromwales Posted February 15, 2021 Share Posted February 15, 2021 57 minutes ago, PeterW said: I’d have the boost one as the one through the coil then. +1 1 Link to comment Share on other sites More sharing options...
Gav_P Posted February 15, 2021 Author Share Posted February 15, 2021 (edited) 1 hour ago, PeterW said: I’d have the boost one as the one through the coil then. What length is the immersion ..? Both 11” Currently the other way round... I think I’ll swap them over then. Edited February 15, 2021 by Gav_P Link to comment Share on other sites More sharing options...
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