Central Heating extension

[Davey]

I would appreciate some thoughts on this. I have an old house, with a thatched roof. The bedrooms all have gable-type ceilings, ie the first three feet of the walls are vertical, then they slope to a higher level. The two guest rooms have central heating radiators, the master bedroom does not. As I get older, I need the heat, and electricity is getting very expensive, more than the cost of oil. Due to the furniture which lives in the bedroom, and the only layout for where to put the bed, the only available space for a radiator is in front of the defunct fireplace. It is defunct because of the thatched roof, which would require extensive and expensive chimney insulation work before it could be used safely, so blocking it with a radiator is no problem. There is zero chance of the chimney being used in the future, at least while I am still living here. In an adjacent cupboard, there are two pipe connections that are spare supply and return pipes for the CH system. So far, so good. The question is about making the connections to a new radiator. Clearly, a new radiator can be installed, with suitable support, in the fireplace. But is it possible to use flexible or otherwise removable pipe connections so that the radiator could be isolated and temporarily removed at some later stage, if access was needed to the chimney behind the fireplace? I am thinking of an isolating valve in each of the pipes, possibly a short piece of flexible hose, and a local drain valve or two to empty just that section of piping and the radiator if required. It seems do-able to me, but are there any rules or pitfalls that I might need to concern myself with? Any help most welcome.

[David Wade]

Its normal to fit valves to both ends of a radiator. Normally one is used to adjust the flow rate, and the other to turn the radiator off if the room is not in use. On a "modern" system the second is usually a thermostatic valve that adjusts the flow according to temperature, or it can be an electronic valve. These valves can be also used to isolate the radiator so it can be removed. Things are usually arranged so there is enough flex in the pipes to allow this. It can be a bit messy getting a bowl under the end but it can be done.

If you want more access then you can fit additional valves, so a section of pipe could be removed.

I don't believe there are any rules. My only concern is where is the main thermostat. Will the room get warm enough before it kicks in. You might want to look at a system like Drayton Wiser or Tado which give the equivalent of a multi-zone system by using temperature sensing wireless operated radiator valves

Dave

[alan_m]

As has already been pointed out you would normally have a valve at either end of the radiator that can be fully turned off. It's then a shallow bowl or empty margarine tub to catch the water from just the radiator (also have a bucket handy for when the bowl/tub overflows)

Are flexi connections rated for "continious" hot water that may be circulated in a CH system? I know they are used (and use a couple myself) for connections to hot water taps but these intermittently have hot water running through them. Some flexi connectors are only rated to 60C.

The hose inside the flexible tube is a much smaller bore than the outside strengthening mesh. Pick the wrong flexi and you could be seriously restricting water flow.

Much better to use solid copper pipe connected to your exiting system with compression fittings and a couple of service valves. This way you could just undo the compression fitting to remove the pipe(s). Select a good quality branded isolation valve rather than a no-name cheaply. Sods law dictates that irrespective of how much you have paid for the isolation valve it will be either seized when you come to need it in many years time or it will drip after being subsequently tuned back on :(

[Theo]

I'm not sure about 'flexi' connections (ie the ones with metal mesh outside like shower hoses), but PEX or polybutylene (barrier) pipe is rated for continuous use, and many heating systems are plumbed that way. PB is more flexible than PEX.

Copper has its advantages, but flexible pipe can be a lot easier to run if you need to get through an awkward space. It comes with a 50 year guarantee so not much concern about longevity.

Theo

[Davey]

Thank you, everybody. I did not think that my Honeywell Thermostat valves were ok for full isolating shutoff, but maybe they are. Interesting to read about the different Flex types.

More pondering to be done, and then to find somebody who will do such a small job. Thanks.

[John Rumm]

A rad will normally have valves at each end, so removing that is easy enough.

If you want the pipework to be moveable as well, then you could plumb it in PEX Speedfit or any other barrier pipe rated for normal domestic use. That would allow the pipes to be moved out of the way (while still remaining attached to the system) once the rad is disconnected at it's valves.

If you want removable rigid pipe, then fit compression service valves to the existing CH pipework, and then you can disconnect the pipe at the compression fitting on the valve.

[SteveW]

As others have said, plumbing in copper or PEX Barrier pipe and fitting valves to both ends of the radiator is the norm. There is enough flexibility to remove the radiator from between the valves.

There are normally different valves at each end (often the same type, but with different caps). One has a cap with grooves for you to grip, to turn it on or off (or in between), so that you can occasionally adjust it for your requirements. The other has a smooth cap, that reveals a stem when the cap is removed. That is only adjusted as part of balancing the system or for temporary isolation.

The balancing valve can be bought with an integral drain valve, allowing you to isolate both ends of the radiator, open the bleed valve and then open the drain valve to empty the radiator before loosening the valve nuts for removal. It makes life a whole lot easier for decorating, etc.

[alan_m]

TRVs usually come with a plastic decorators cap - often discarded during installation or lost in the mists of time. You unscrew the TRV head and screw back on the decorators cap. This fully depresses the plunger and fully turns off the valve. As someone suggested in this group recently the same may be achieved by unscrewing the TRV head and inserting a 5p coin between the head and plunger pin (with the head screwed back on and set to minimum)

[Tricky Dicky]

The SS flexible pipe can be used on CH systems, my kitchen kickspace heater came with two lengths for connection to the fixed pipes. Mind you with the previous kickspace heater we had I had to replace one of the pipes as it became blocked. I never really investigated why just went ahead and replaced it.

Richard

[Davey]

That last bit is useful, thanks.

[Davey]

Ah, I didn't know about the decorator's cap. All my valves were installed years before I moved in. Thanks for the information.

[Tim+]

My mother’s bathroom radiator/towel rail was plumbed in with this stuff but the radiator never worked properly and then stopped working altogether. When I replaced the flexible sections, the bore was totally occluded due to swelling of the lining. This stuff was rated for hot water but not for use in a CH system I think.

Looks like her plumber didn’t know the difference.

Tim

[Brian Gaff]

I'd also suggest something to isolate the chimney thermally so all you heat is in the room not going up the chimney. Brian

[Davey]

Thanks, but already in the plans. But I want to be able to get to it if absolutely necessary in case anything gets stuck in there, hence requirement for ability to remove the radiator.

[alan_m]

Fit an appropriate cap to the chimney pot. perhaps something like

[Davey]

The cost is in the fitting of it, there is no way for ladders to get up there, so it's scaffolding. At a cost.

[alan_m]

If you block up the bottom and install insulation in the opening then you need to stop the rain entering from the top.