Towel Radiator Plumbing

[Schmill]

Hi all,

I just wanted to make sure that the following plumbing plan will work for a bathroom towel radiator that needs to be on whenever the boiler is running, irrelevant of whether it is doing Hot Water or Central Heating.
My system is indirect heating vented system with pumped primary;

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• Schmill
• 9 Jan 2011
• 1

The system as it was is the blue sections, and the red section is where the plumber has tied in the bathroom towel radiator. He mad the connections whilst I was refitting the bathroom and the new connections are now under the bath leading to 2 capped pipes ready for me to connect the towel rail to.
However since reading a bit on here, I'm not sure if the feed to the towel rail, (the top red pipe), should come AFTER the pump and before the valves?
I can see why it has been done the way it has, as it meant the plumber could do all the work in the bathroom rather than having to run fresh pipework back to the airing cupboard.
I just want to make sure it will work ok before connect up the rail and board over the section of floor.
I'm hoping that as long as I close down the balancing valve on the towel rail to the right point water will still flow through the boiler and the towel rail....
Just after some second opinions please

 

[Rob]

No. Needs to be after pump but before the motor valves

 

[Schmill]

So the above will NOT work?

If not I am going to have to tear up my landing, so I just want to be sure first...

This is my aircupboard pipework:

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• Schmill
• 21 Oct 2010
• 2

There is almost no room between the valves and the pump... I guess I might be able to squeeze in a T on the horizontal section after the pump and before the valve?

 

[slup]

I can't see why it wouldn't work. You've still got a flow and return - the position of the pump is immaterial.

I'm not a plumber - just looking at the diagram from a pragmatic point of view!

You'll need to be careful not to open the valves too wide on the towel radiator though?

 

[spraggo]

So the above will NOT work?

You need to insert the flow to the towel rail between the pump outlet and the horizontal pipe going into the MV as you suggested. If you fit it as per your drawing the towel rail will act as a bypass and instead of the water circulating through the boiler it will circulate through the towel rail. I note that in your photo you have the flow marked as the return.

spraggo

 

[ChrisR]

Rob's right in that it's the wrong way to do it. On the face of it there's no pressure to send water trough the Towel Rail.
But in practice There WILL be some pressure across the TR whenever the water's flowing, because of the resistance of the boiler. Newer boilers are much more resistive than old ones. See your boiler manual!

If you have a 5meter head pump, your pressures might be like this, relative to the standing pressure where the fill meets the circuit:

In that case, ther's half a meter of head across the towel rail, which is loads.

If you open the TR valves wide, there would be almost no flow through the boiler though - hence not a good thing! If you can just open them a tiny bit, then maybe it would work.

Better, would be to put a tee in after the pump, and connect that to the flow side of the towel rail. You need very little flow to heat up a towel rail, so I'd think first about getting 10mm plastic through.
There's what a plumber would think of as loads of space by the motorised valve - or just raise the pump.

Your photo shows "Return" as in return to the pump, but Flow and Return are normally used in relation to the flow From and To the boiler,

 

[Schmill]

So the above will NOT work?

You need to insert the flow to the towel rail between the pump outlet and the horizontal pipe going into the MV as you suggested. If you fit it as per your drawing the towel rail will act as a bypass and instead of the water circulating through the boiler it will circulate through the towel rail.

Cr@p that's what I was fearing
So now what would have been a 20 minute job for the plumber in the first place as he would have had direct access from the void under the bath into the airing cupboard, is now going to take me AGES as I am going to have to take up the flooring on the landing and take the 'long' route.
Regarding the 2 T-offs the plumber already fitted, (imagine the red pipes in my drawing, but without the towel rail connecting them), will they be ok to just cap off and leave? I can't really cut them out as I don't have access to that area of the pipe work anymore

I note that in your photo you have the flow marked as the return.

spraggo

Yeah, thanks for that, it's an old picture and I had marked up the flow and return relative to the pump rather than relative to the boiler!

 

[ChrisR]

If it's that hard, try it as it is. I've seen it work fine like that - until someone opens the TR valves too much.

What's the boiler, and how far is it from the towel rail?

 

[spraggo]

imagine the red pipes in my drawing, but without the towel rail connecting them), will they be ok to just cap off and leave? I can't really cut them out as I don't have access to that area of the pipe work anymore
[/quote]


You only need to blank off the flow, the return will be OK.

 

[Schmill]

If it's that hard, try it as it is. I've seen it work fine like that - until someone opens the TR valves too much.

What's the boiler, and how far is it from the towel rail?

The boiler is an oldish (was in the house when we moved in 4 years ago, no idea how long it has been here), British Gas branded "Ideal RD2 450".

It is downstairs in the kitchen, and the towel radiator and pump etc are upstairs. There would be probably 7.5m of 22mm pipe (including travelling vertically from upstairs to down), between the boiler and the current towel rail T-off points. The actual towel rail is then about 2m of 15mm pipe away from the T-off points too.

The towel radiator itself has one TRV valve and one lock-shield valve, if that makes any difference.

You only need to blank off the flow, the return will be OK.

Cheers, and just to be SURE, the 'Return' would be the bottom red pipe in my drawing, as in the return to the boiler? The flow T-off could just be capped off and left as a branch that goes nowhere (if I end up not using it?)

 

[spraggo]

Cheers, and just to be SURE, the 'Return' would be the bottom red pipe in my drawing, as in the return to the boiler? The flow T-off could just be capped off and left as a branch that goes nowhere (if I end up not using it?

Come on with respect to you can`t be that thick and whats the point in having a TRV on a towel rail?.

 

[ChrisR]

Come on with respect to you can`t be that thick and whats the point in having a TRV on a towel rail?.

Every point! It's going to be getting hot in the summer!!

The boiler /pipe would be giving you enough resistance to "play" with, I think. The lockshield would have to be very nearly closed - just "cracked" open. Think about drippng hot tap - it gets pretty warm.

 

[Schmill]

Cheers to all.

and yeah, the reason for the TRV is because although I want to dry my towels in the summer I don't want to be boiling the bathroom!

So the general opinion is;

It might / could work the way it is currently setup, but the BEST way of doing it would be to run in a feed from between the pump and the zone valves to the towel rail.
I guess if I rotate the bottom motorised valve so that the motor head is on the other side of the pipe, (towards the right of the photo), then that would give me room to put a branch in between the T to the 2 valves, and the left hand valve...
Ok, next stop will be to see what board I can lift between the airing cupboard and the bathroom, and how many joists I need to notch, guess that will be the deciding factor on which way I end up going with this now.

Thanks again

Hmm... time to go investigate what access I can gain where.

Come on with respect to you can`t be that thick and whats the point in having a TRV on a towel rail?.

Sorry, I wasn't trying to be 'thick' was just making sure that the return you were refering to was the standard understanding of 'return to boiler' rather than what I had labelled as 'return' in my photo, which I had mislabelled as the return (to the pump).
Obviously you are meaning the standard definition, so the return to the boiler T will stay, and I'll look at the possibility of shifting the Feed.

 

[Schmill]

Just in case anyone is interested, and to provide closure to this thread, I decide to do it 'properly' in the end

I managed to get back under the bath and remove the section of floor I needed to (with the bath propped up on blocks of wood!), and managed to completely remove the T section that was providing the 'feed', and replaced it with a straight section of copper.
The return side of the towel rail I left where it was, T-ed into the return to the boiler.

For the Feed I ended up moving the pump up the pipe slightly and fitting in a T after it to take a 15mm copepr feed to the towel rail.

Apart from some annoying air in the system it all seems to be working well now. Thanks everyone for the advice

New airing cupboard piping shown below;

Bottom of Heating Pipe work (w/towel rail feed)

• Schmill
• 7 Apr 2011
• 2