Brill will give it a go. Presumably find a decent box for all wires and about 15 wire holes. Just mount relay on a din rail?
Central heating wiring with ufh plus rads
- Thread starter an203888
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You can go DIN rail if you want, or get an 8 pin or 11 pin base and screw it to the back of the box or you can be shoddy like me and just tuck it in a corner somewhere...see pic 
EDIT. That's a plastic box about 250mm x 250mm x 100mm deep. Terminal blocks are mounted on a backboard to make it easier to wire in to. I've done it the telecom way- cabling from thermostats, pumps, timeclocks etc comes into the blocks and link wires go between the blocks. There's a lot to be said for having an earth block and a neutral block for all the common stuff but there we go, its in, it works
EDIT. That's a plastic box about 250mm x 250mm x 100mm deep. Terminal blocks are mounted on a backboard to make it easier to wire in to. I've done it the telecom way- cabling from thermostats, pumps, timeclocks etc comes into the blocks and link wires go between the blocks. There's a lot to be said for having an earth block and a neutral block for all the common stuff but there we go, its in, it works
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I see the problem, but not the solution, the problem is the boiler is analogue, and most zone valves are digital i.e. on or off, so what is needed is enough zone valves so the net result emulates a analogue control.
The UFH is split into many zones each one with water at around 30°C each time the water cools some more hot water is added, and the water is pumped around in a circle of just the UFH with an independent pump to the one which pumps main CH water around. So although the valves are digital the net result with a bank of 10 valves on the manifold is near enough analogue.
The UFH will not react fast enough to compensate when the sun shines through a window, so you need the radiators to act fast, so they can turn off fast when sun comes out, so need electronic TRV heads to work fast enough, so if you have electronic TRV heads, you can set zones without using a zone valve, so the on/off zone valve becomes redundant, so you now have one thing left.
As the weather gets warmer you want the whole system to turn off, tradition was a single wall thermostat placed in a room normally kept cool, with no outside doors, or alternative heating, on the ground floor, if such a room does not exist, then fit more than one you can fit as many as you like in parallel, main thing is they need to be set higher than the TRV in that room, they only work when weather improves, they do not regulate room temperature, all they do is stop the boiler cycling on/off through the summer months.
Old house I had two wall thermostats, one in kitchen and one in hall, neither ideal rooms, but as a pair they worked well. Did not want one in living room as living room kept too warm, want the wall thermostat at around 18°C so on warm days boiler does not even run first thing in morning.
If going to the expense of UFH then the cost of wifi TRV is not that high, between £40 and £80 each depending on the make, these can replace the wall thermostat, there is one make called Hive where the TRV head sends a 'demand for heat' to the wall thermostat, so if the wifi heads are put in coolest rooms, does not need to be every room, the wall thermostat also in a cool room and between them they can insure the boiler runs when required, you can use cheap eQ-3 at £10 each in rest of rooms. If when in use you find one room cold, just add a wifi TRV to that room.
TRV heads do come in different quality, think Drayton is about the best, with algorithms built in to work out when to turn down so rooms heat up fast but do not over shoot, however not found a single make that does everything, EPH wall thermostats can be set master/slave and work with OpenTherm with many wall thermostats, but no link to TRV heads, Nest has a really good algorithm but again does not link to TRV head, Hive is rather basic with no OpenTherm, but does link to TRV heads, the list goes on.
The guys who fit central heating call themselves heating engineers, and to be frank to work out the best most economic way to heat the home will likely mean training to degree standard, as an electrical engineer I realise the skill required to select the right product and set it up to work well, and also realise I don't have that skill, if designing a heating system was easy the guys doing it would not need to train to degree standard, I had three attempts at mothers central heating before I got it right, this house still not right, electronic TRV's in every room helps, but is not the whole solution.
So if your going to DIY expect to make errors, I know here the wall thermostat (Nest Gen 3) was not in hind sight best option, I feel not my error, when I bought the Energine TRV heads I was told they worked with Nest, but when I came to pair them up with Nest was told Nest has withdrawn support. So they work well enough not to be worth changing, but not A1.
The UFH is split into many zones each one with water at around 30°C each time the water cools some more hot water is added, and the water is pumped around in a circle of just the UFH with an independent pump to the one which pumps main CH water around. So although the valves are digital the net result with a bank of 10 valves on the manifold is near enough analogue.
The UFH will not react fast enough to compensate when the sun shines through a window, so you need the radiators to act fast, so they can turn off fast when sun comes out, so need electronic TRV heads to work fast enough, so if you have electronic TRV heads, you can set zones without using a zone valve, so the on/off zone valve becomes redundant, so you now have one thing left.
As the weather gets warmer you want the whole system to turn off, tradition was a single wall thermostat placed in a room normally kept cool, with no outside doors, or alternative heating, on the ground floor, if such a room does not exist, then fit more than one you can fit as many as you like in parallel, main thing is they need to be set higher than the TRV in that room, they only work when weather improves, they do not regulate room temperature, all they do is stop the boiler cycling on/off through the summer months.
Old house I had two wall thermostats, one in kitchen and one in hall, neither ideal rooms, but as a pair they worked well. Did not want one in living room as living room kept too warm, want the wall thermostat at around 18°C so on warm days boiler does not even run first thing in morning.
If going to the expense of UFH then the cost of wifi TRV is not that high, between £40 and £80 each depending on the make, these can replace the wall thermostat, there is one make called Hive where the TRV head sends a 'demand for heat' to the wall thermostat, so if the wifi heads are put in coolest rooms, does not need to be every room, the wall thermostat also in a cool room and between them they can insure the boiler runs when required, you can use cheap eQ-3 at £10 each in rest of rooms. If when in use you find one room cold, just add a wifi TRV to that room.
TRV heads do come in different quality, think Drayton is about the best, with algorithms built in to work out when to turn down so rooms heat up fast but do not over shoot, however not found a single make that does everything, EPH wall thermostats can be set master/slave and work with OpenTherm with many wall thermostats, but no link to TRV heads, Nest has a really good algorithm but again does not link to TRV head, Hive is rather basic with no OpenTherm, but does link to TRV heads, the list goes on.
The guys who fit central heating call themselves heating engineers, and to be frank to work out the best most economic way to heat the home will likely mean training to degree standard, as an electrical engineer I realise the skill required to select the right product and set it up to work well, and also realise I don't have that skill, if designing a heating system was easy the guys doing it would not need to train to degree standard, I had three attempts at mothers central heating before I got it right, this house still not right, electronic TRV's in every room helps, but is not the whole solution.
So if your going to DIY expect to make errors, I know here the wall thermostat (Nest Gen 3) was not in hind sight best option, I feel not my error, when I bought the Energine TRV heads I was told they worked with Nest, but when I came to pair them up with Nest was told Nest has withdrawn support. So they work well enough not to be worth changing, but not A1.
The underfloor heating pump keeps the underfloor heating water circulating all the time. If you used one pump, the thermostat in the manifold would close when the UFH water reached its set point of around 30 degrees and then the single pump wouldn't be able to circulate the water in the UFH circuit.
Hence two pumps.
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I seem to remember not all under floor heating works that way, there is a single pump version, although told not that good.
I would be tempted to put the radiator and UFH in series so the radiator can cool the water first, but think this would not be permitted as you could not be sure the floor did not exceed the 27°C limit.
I like the idea of UFH it has been around some time
but the problem is control, and as I found when I returned to mothers house to look after her, it depends on house design as well as heating design, her house had a lovely bay window, which caught the morning sun, when I came to move back in found living room at 32°C as the sun had hit the windows and the radiator was slow to cool, (Room set to 20°C) swapping the wax TRV head for an electronic head improved it, 24°C max recorded after. However my open plan house we had never had that problem, bedroom getting too hot yes, but not main living room.
The big problem with UFH is speed, slow to heat and slow to cool, likely ideal in an old peoples home where heating never turned off, and hot radiators can be a danger, and son used it as a heat sink for the aga cooker, it took the heat away from side water heater so it did not boil, and warmed the bedrooms.
Having now lived in this house for a year I would consider it in dinning room and kitchen, but no way would I fit it to living room, as morning sun can heat it too fast, so at 7 am the radiators are at full temperature trying to heat room, but 15 minutes after the sun pops over the hill, room temperature can jump, so want to stop heating the room. And under floor heating too slow to respond.
But as said all down to house design, it is easy once installed and running to see errors, but needs a lot of skill before it is fitted to work it out, even a tree in the garden can change things and stop direct sun light warming the room.
I would be tempted to put the radiator and UFH in series so the radiator can cool the water first, but think this would not be permitted as you could not be sure the floor did not exceed the 27°C limit.
I like the idea of UFH it has been around some time
but the problem is control, and as I found when I returned to mothers house to look after her, it depends on house design as well as heating design, her house had a lovely bay window, which caught the morning sun, when I came to move back in found living room at 32°C as the sun had hit the windows and the radiator was slow to cool, (Room set to 20°C) swapping the wax TRV head for an electronic head improved it, 24°C max recorded after. However my open plan house we had never had that problem, bedroom getting too hot yes, but not main living room.The big problem with UFH is speed, slow to heat and slow to cool, likely ideal in an old peoples home where heating never turned off, and hot radiators can be a danger, and son used it as a heat sink for the aga cooker, it took the heat away from side water heater so it did not boil, and warmed the bedrooms.
Having now lived in this house for a year I would consider it in dinning room and kitchen, but no way would I fit it to living room, as morning sun can heat it too fast, so at 7 am the radiators are at full temperature trying to heat room, but 15 minutes after the sun pops over the hill, room temperature can jump, so want to stop heating the room. And under floor heating too slow to respond.
But as said all down to house design, it is easy once installed and running to see errors, but needs a lot of skill before it is fitted to work it out, even a tree in the garden can change things and stop direct sun light warming the room.
All wired in and seems to work a treat. My box is like spaghetti junction inside but will tidy up later. Thanks for help.
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