ProDave Posted January 17, 2019 Share Posted January 17, 2019 16 minutes ago, newhome said: If the UFH is off all summer for example doesn’t the water in the loops go manky? And then you’re potentially showering with that water when it eventually feeds back into the TS? Or have I got that wrong too lol? It should have inhibitor in it to stop it going manky. And you don't shower with the water in the TS, that never gets changed. You shower with fresh water that passes through a coil in the TS, or a heat exchanger to get heated by the heat in the tank. 1 Link to comment Share on other sites More sharing options...
newhome Posted January 17, 2019 Share Posted January 17, 2019 Wow, and there was me thinking the shower water came out of that tank! Is that different to an UVC then? Link to comment Share on other sites More sharing options...
ProDave Posted January 17, 2019 Share Posted January 17, 2019 Yes, the water in a UVC is the water that comes out of your hot tap, and every time you draw some off, fresh mains cold water goes into the bottom to replace it. With a UVC, the heating system is a separate closed loop, and the heating loop from the boiler or heat pump etc passes through a coil in the UVC to heat it. 1 Link to comment Share on other sites More sharing options...
newhome Posted January 17, 2019 Share Posted January 17, 2019 Every day’s a school day ? ?? Link to comment Share on other sites More sharing options...
Onoff Posted January 17, 2019 Author Share Posted January 17, 2019 4 hours ago, newhome said: Every day’s a school day ? ?? Out of interest do you understand how a traditional CH/DHW (like mine) works? Not a bad idea going Baxter Basics if you want to understand these things. One thing seeing a drawing... Link to comment Share on other sites More sharing options...
newhome Posted January 17, 2019 Share Posted January 17, 2019 19 minutes ago, Onoff said: Out of interest do you understand how a traditional CH/DHW (like mine) works? Not a bad idea going Baxter Basics if you want to understand these things. Nope! Boiler comes on and if a combi heats water on demand, or if not has a tank to hold said hot water until needed. Water circulates to rads (somehow) and if they have thermostatically controlled values individual rads shut off when temperature is at the set level. Most systems have a single thermostat that shuts boiler off when at that temperature. How the water gets to the rads I've no idea . Air gets in sometimes and rads need to be bleeded (cos I've done that bit before ). Other than that I'm clueless . Link to comment Share on other sites More sharing options...
Onoff Posted October 21, 2019 Author Share Posted October 21, 2019 I need to resurrect this idea. Got down to 16 in the bathroom the other day. This is just now (yes I still need to touch the ceiling up where I fitted the fan): Is there no way of having a buffer tank with expansion tank that doesn't need an annual G3 inspection? Link to comment Share on other sites More sharing options...
PeterW Posted October 21, 2019 Share Posted October 21, 2019 Yes - but your buffer has to be indirect so the coil is pressurized as part of the boiler circuit and the tank then feeds the UFH with either a small header or just a small expansion vessel. Link to comment Share on other sites More sharing options...
Ed Davies Posted October 21, 2019 Share Posted October 21, 2019 1 hour ago, PeterW said: …or just a small expansion vessel. Assuming the buffer and UFH pipework between them are over 15 litres, wouldn't such an unvented system need inspection? If not, what's the difference? Link to comment Share on other sites More sharing options...
Jeremy Harris Posted October 21, 2019 Share Posted October 21, 2019 It also needs a low pressure relief valve, as most tanks that are intended to be vented are only rated to around 1.5 bar max. Even with an EV, which will need to have its charge pressure set to something like 0.5 bar, there is still a risk that the system pressure could exceed the burst pressure of the tank if there's a fault (something like the EV losing its charge). A small header tank gets around the problem. As @ProDave says, this need not have a float valve, overflow etc, it could be a small tank like one of these: https://www.tanks-direct.co.uk/water-tanks/water-storage-tanks/10-50-litre-water-tanks/12-litre-water-tank-t12na-4.html fitted with a vented cap and bottom outlet. Just need to check the level from time to time. Link to comment Share on other sites More sharing options...
PeterW Posted October 21, 2019 Share Posted October 21, 2019 36 minutes ago, Ed Davies said: Assuming the buffer and UFH pipework between them are over 15 litres, wouldn't such an unvented system need inspection? If not, what's the difference? not really as G3 doesn’t apply to buffer tanks as they are not used to hold wholesome hot water, or are not used to heat other water. It’s open to interpretation as to whether it is “all tanks” as the latter point could refer to an indirect buffer tank. The usual issue is that a standard cylinder can’t cope with more than 1.6bar, but a decent stainless buffer can cope with more than that but is twice the price. Link to comment Share on other sites More sharing options...
Onoff Posted October 21, 2019 Author Share Posted October 21, 2019 Thanks all. Does anyone have a generic diagram of what I need? Been looking to no avail. So @JSHarris, I can site one of those plastic tanks with a vent cap, above my vented indirect copper cylinder that I want to use as a buffer? No G3? Link to comment Share on other sites More sharing options...
PeterW Posted October 21, 2019 Share Posted October 21, 2019 3 minutes ago, Onoff said: Thanks all. Does anyone have a generic diagram of what I need? Been looking to no avail. So @JSHarris, I can site one of those plastic tanks with a vent cap, above my vented indirect copper cylinder that I want to use as a buffer? No G3? que..? Have you got an indirect tank ..? So are going to put the coil into the heating system and then take the hot from this into the UFH..?? Link to comment Share on other sites More sharing options...
Onoff Posted October 21, 2019 Author Share Posted October 21, 2019 3 minutes ago, PeterW said: que..? Have you got an indirect tank ..? So are going to put the coil into the heating system and then take the hot from this into the UFH..?? Something like this on page 1. Existing single pipe heats the tank indirectly... Link to comment Share on other sites More sharing options...
PeterW Posted October 21, 2019 Share Posted October 21, 2019 Just don’t complicate and put the towel rad on the radiator circuit and be done with it ... Link to comment Share on other sites More sharing options...
Nickfromwales Posted October 22, 2019 Share Posted October 22, 2019 Wouldn’t a decent LLH suffice here? Example Link to comment Share on other sites More sharing options...
Onoff Posted October 22, 2019 Author Share Posted October 22, 2019 1 hour ago, Nickfromwales said: Wouldn’t a decent LLH suffice here? Example Link not working... Link to comment Share on other sites More sharing options...
PeterW Posted October 22, 2019 Share Posted October 22, 2019 Try this https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F290952966223 1 Link to comment Share on other sites More sharing options...
Onoff Posted October 22, 2019 Author Share Posted October 22, 2019 1 hour ago, Nickfromwales said: Wouldn’t a decent LLH suffice here? Example Aside from the price and how it's fitted! I might not have baulked at the price if I understood it! Off to read the ad again then Google for typical circuit. Link to comment Share on other sites More sharing options...
Jeremy Harris Posted October 22, 2019 Share Posted October 22, 2019 9 hours ago, Onoff said: Thanks all. Does anyone have a generic diagram of what I need? Been looking to no avail. So @JSHarris, I can site one of those plastic tanks with a vent cap, above my vented indirect copper cylinder that I want to use as a buffer? No G3? Yes, should be fine. The tank will work as a fill and expansion tank, to cope with the change in volume as the tank heats up and cools down. Just need to watch the level, in case there's a leak, plus the very small evaporation loss (with the vented lid on the evaporation loss should be very low). Link to comment Share on other sites More sharing options...
Onoff Posted October 22, 2019 Author Share Posted October 22, 2019 Right, just watched a little GIF of how things work. Seems you have primary and secondary flows and returns. Struggling to see the point. It won't keep the dirty old system separate from the new circuit(s)...will it? Link to comment Share on other sites More sharing options...
Jeremy Harris Posted October 22, 2019 Share Posted October 22, 2019 Just now, Onoff said: Right, just watched a little GIF of how things work. Seems you have primary and secondary flows and returns. Struggling to see the point. It won't keep the dirty old system separate from the new circuit(s)...will it? No, a LLH doesn't provide any separation. 1 Link to comment Share on other sites More sharing options...
Onoff Posted October 22, 2019 Author Share Posted October 22, 2019 Just now, JSHarris said: No, a LLH doesn't provide any separation. That's out then! Link to comment Share on other sites More sharing options...
PeterW Posted October 22, 2019 Share Posted October 22, 2019 4 minutes ago, Onoff said: Right, just watched a little GIF of how things work. Seems you have primary and secondary flows and returns. Struggling to see the point. It won't keep the dirty old system separate from the new circuit(s)...will it? put a decent magnaclean in the system to start with. Link to comment Share on other sites More sharing options...
Onoff Posted October 22, 2019 Author Share Posted October 22, 2019 4 minutes ago, PeterW said: put a decent magnaclean in the system to start with. How often do you clean them out? I assume you just use the isolation valves on them, unscrew and empty the crud? Link to comment Share on other sites More sharing options...
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