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Adding new radiator(s)

Discussion in 'Plumbing and Central Heating' started by sotal, 7 Nov 2020.

  1. sotal

    sotal

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    I'm currently having some building work done.

    As part of this I'll be adding a radiator. This will be more or less directly above the boiler. The 22mm flow and return pipes run straight past where I want to put the radiator, so I was going to just tee in and run 15mm to the new radiator.

    That was all simple enough but then as I've just been looking at the current setup, I figured I would be better to simplify another radiator in the house. It was one we had added a few years back to give a radiator in the utility room which previously didn't have one. If the access had been available at the time it would have been much better to have tee'd off in the same place as I'm about to, but that wasn't possible at the time without major disruption, so instead they tee'd off on the main flow and return loop in the house, and ran pipes about 7m long through the garage to the utility. I've never liked the idea behind this and although they are lagged it must be inefficient as the 22mm pipes run one way above then it runs all the way back again.

    So my thoughts are to disconnect and remove the long pipe to this radiator and plumb it in much closer to the boiler along with the new rad.

    The difficulty I will have is space to do it. There isn't quite space to do two tees in that spot.

    So I could do one tee and then split the 15mm to go to two radiators. Would that work?

    Or I could add another T a bit further down the line, but then route the 15mm pipe back.

    The new rad is basically above the old one that I would like to replumb.

    I'm guessing two separate Tees off the 22mm would be better but just wanted to check as the other way would be easier to plumb!

    Thanks
     
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  3. oldbuffer

    oldbuffer

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    1. If you have a combi boiler, this will be ok.
    2. If you have motorised valves in the system, you would be picking up heat whenever the boiler is on, for heating OR hot water. Also, the hot water cylinder return would no longer be the last connection to the return before the boiler, which can give reverse circulation problems.
    3. Could you not come off the flow and return with 22 mm equal tees, a short length of 22 mm pipe to a 22:15:22 tee then another short length of pipe to a 22:15 reducer?
     
  4. sotal

    sotal

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    Thanks for the reply. It is not a combi boiler. It is a conventional system.

    We have the storage tanks in the loft, a hot water cylinder in the airing cupboard and the boiler in the utility room behind the garage. It has a Y valve in the airing cupboard.


    It is a slightly awkward layout due to the house being extended in the 80s.

    As you rightly point out, if I tap off where I had planned to, then it will always come on whenever the boiler runs.

    So really my other choice would be to join onto the radiator that is below, but that one is already on the end of about 7m of 15mm. Can I put a 15mm T on each pipe just before this rad, or would that not work well?

    To take another T off the 22mm would mean another long run.
     
  5. oldbuffer

    oldbuffer

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    1. Can't answer the "would that not work well" without knowing what is already running off that section of 15 mm. (No. of radiators, kWattage / size & type).
    2. Could you replace the 7 m run of 15 mm with 22 mm? If yes, you could almost certainly run another radiator off it.
     
  6. sotal

    sotal

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    Currently the 7m of 15mm goes to a towel radiator style radiator in the utility room. It isn't thermostatically controlled. I can't remember the BTU but I remember it was specified as one that would hear the room as many of the towel radiator were low output. It is about 6 foot high in total but is obviously tubular so not like having a solid 6 foot high radiator.

    I'm looking at adding a radiator that would heat an ensuite of 3m X 1.7m.
     
  7. oldbuffer

    oldbuffer

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    1. Have a look for a radiator similar to the one in your utility room. Pick the closest in size and note the wattage of it. Most of them are around 500 to 600 watts.
    2. 15 mm pipework will handle around 3 to 4 kW. If your utility is, say, 600 then you have 2.4kW to account for the heat loss from the new radiator and any heat losses from the pipe run.
    3. In my opinion (no guarantee!) you will need around 1 to 1.5 kW for the new radiator.
    4. Taking the mean new radiator power this would leave just over 1kW for pipework losses.
    5. Given the above, I'd just tee it off the existing radiator pipes. Should be OK, and would be even better if you could insulate (at least in part) the existing 7 M 15 mm run.
     
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