To comply with Approved Document Part L, you need a boiler interlock that totally cuts boiler heating when the house is warm. The two main methods (although any method you can think of would be fine) are:
A room thermostat in a room without a TRV and TRVs in all other rooms.
TRVs on all radiators and a flow sensor to cut boiler power when all are closed.
Method 1 can be divided into separate zones, each with their own timing and temperature settings. In these cases, you need a room thermostat per zone. You can even subzone to the room level, in which case, there will be no TRVs at all, as all rooms will have a room thermostat and, hence, don't need TRVs. Method 2 is rarely used.
As a rule, it is best to install programmable thermostats and leave the boiler programmer (if present) on 24 hours. This is because a programmable thermostat has certain features that are rarely implemented at the boiler.
a) Programming/manual override can be done in the comfort of your living room, rather than a skanky unlit cupboard under the sink.
b) "Off" doesn't mean off. It means a separate night temperature, such as
10C, preventing condensation, damp and frost.
c) The thermostat can make predictions about how long it will take to warm up and anticipate the temperature change by the appropriate amount.
Plastic where hidden. Chromed copper on display. If you do it right, you can used 15mm chromed copper for the last 30cm between the radiator and under the floorboards and plastic elsewhere.
I would use an automatic bypass valve rather than a radiator. For the towel rail on a combi boiler, I'd plumb it like a normal radiator with its own TRV (or zone), but consider an additional electric element wired to a 1 hour boost button for summer preheating of towels.
I would endorse most of what Christian McArdle has replied.
You don't say wether you are going for a combi boiler or stored HW. If the former then likely the bypass is done internally in the boiler. If the latter then I'd put the bathroom towel rail on as the bypass. Theoretically you don't need a bypass if using Y plan (3 port valve) controls (but I'd recommend S-plan + bathroom towel rail as bypass).
If using chromed copper, note that you will have to: Either use a compression fitting onto the plastic and you MUST use the correct sleeve supporting inserts on the plastic. Or you can abrade the chrome pipe to copper and use a push fit connector.
If you have suspended floors to route the plastic pipe through, you will need a right-angle drill or driver (not a £10 plastic gear box) to bore the joists. But the jobs become a dream as you drag the plastic from A to B as one run!
Arrrh fellow bodger, please to meet you. I'm about 1 yr ahead of you, and had to answer some very similar questions.
Mine is a bog standard 3 bed semi also, wall mounted thermostat (Combi is programmable on the front of it) in the hallway, all rads with TRVs (looks good for the resale), ones in the hallway and kitchen open full all the time. I placed a 15mm copper bypass at the end of the run (furthest point from the combi) between flow in and out on the hallway rad under the floorboards. Within the bypass I placed a stopvalve just incase all flow went this way and I could close it a little (I never used it, but I'm pleased it's there)
Radiator as a bypass not a good idea, flow in is restricted in and out of radiator, 6mm rings a bell (not too sure though) so you'd need two rads open all the time to get to 12mm. You need a 15mm bypass so hence build a bypass into it, be sure to place it at the end of the run though.
Me I placed a wooden towel rail above a K2 (double radiator with fins in between) rad in the bathroom, towels dry very quick.
-> Heated towel rail on a combie ... dunno, sure it's possible though.
URL
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-> Full product search -> keywd radiator Results : click on info (Technical jargon is explained)
HTHs - Oliver. Pop me an email if you think I can help further.
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