Loop at end of CH system

[Cornish Crofter]

Wonder if you guys could help please.

I am currently installing a wetroom and have replaced the old wooden floor with a new concrete floor that will also have a screed.

Also the customer has opted to have his radiator changed for a heated towel rail using the CH system.

Within the old set up that I had to cut back to the next room as it was resting on the earth underneath the old floor was a loop between the flow and return for the radiator.

The rad was the last on the circuit.

One assumes that this was put in place as a cheap way of ensuring that there was a continuous circulation from the flow to the return.

The customer has complained that the old rad never got hot and the new one is doing the same, as I had been adviced by the guy who fitted the new boiler a year or two ao that he didn't fit a bypass valve as he knew there was a loop already in the system. Hence, on his advice I reinstated the loop in the new plumbing.

It has been suggested that I just remove the loop between the flow and return and simply have the new towel rail as the loop. It hasn't got TRVs but hand adjustable valves both sides. Would this be acceptable? All the other rads have TRVs.

Thanks

 

[GrahamM]

No. You remove the bypass and put in your towel rail, what happens if someone closes the valves on the rail? Water circulations stops!
Leave the bypass in place but tee in an automatic bypass valve and have it balanced to the system.

 

[Cornish Crofter]

Thanks Graham

The Towel rail us above a screeded floor, so one assumes fitting an automtic bypass valve there would be a no no as I can't bury it in the screed.

The other think I had thought of was to trace the plumbing back to the next room and put in a loop with an auto bypass valve there, then remove the loop between the tails of the towel rail.

 

[GrahamM]

That would be an option. As long as the CHW can circulate if all TRV's/valves were closed down.

 

[Cornish Crofter]

Thanks, that was the lines I was thinking along as well.

I do have experience of a system failing as the tenant had turned all the rads off. There were only 3 in that house. Essentially he killed the flow and the boiler started steaming etc. Apparently there was some damage to the boiler to boot. My thinking on this job was there are about 15 rads with TRVs. I was under the impression that TRVs would always let some flow through even if they were completely shut off.

The sensible advice IMO has been along the lines of leave or reinstate as was.

I guess I would need to find a 15mm bypass valve ideally. Putting it in will not be a problem as the floor in the next room is timber and there is plenty of space. The loop would be about 4 feet in 15mm pipe away from the last rad/towel rail.

 

[Blackcatgas]

Id remove the loop esp if the rad isnt getting hot. replace the trv in the room where the roomstat is with a lockshield, if the heating was only done 2 yrs ago then Iam assuming it was done to part L standards and there is a room stat.

 

[ferret]

i.d remove the loop , leave towel rail as is and fit auto bypass in a/c

 

[Cornish Crofter]

i.d remove the loop , leave towel rail as is and fit auto bypass in a/c

It's a combi. There is no airing cupboard.

One option suggested to me was fit a loop accross the flow and return as near to the towel rail as poss but fit a gate valve, adjust it to 1/4 open and remove the wheel.

 

[GrahamM]

If you want to do the job correctly fit in a auto bypass. If you want to step back in time fit your gate valve.
One does the job correctly the other gets you by.
You can fit the auto bypass at virtually any point in system as long as its at least 2m or so from the boiler.

 

[Cornish Crofter]

If you want to do the job correctly fit in a auto bypass. If you want to step back in time fit your gate valve.
One does the job correctly the other gets you by.
You can fit the auto bypass at virtually any point in system as long as its 2m or so from the boiler.

Is that less or more than 2m or about 2m?

I take your point about doing the job correctly. The problem is that I need to get the room up to temp to be able to tile it and have a fighting chance of the adhesives going off.

The customer is unwilling to pay to have it altered. If I do then it's looking like I will have to alter it at my expense. That is one reason I liked the idea of the gate valve.

My preference would be to fit the ABV

 

[GrahamM]

Sorry. At least 2m is good practise. Gives the CHW a bit of a circuit then.

 

[justlead1]

Have you considered just using copper to irons to connect rad? Doing away with valves. You may need to restrict flow a bit if it starves other rads.

 

[oldplumber]

does the combi have a built in bypass, most seem to now, so just remove the loop and still leave lockshiels on the towel railas anextra bit of safety and alls well.

 

[Cornish Crofter]

does the combi have a built in bypass, most seem to now, so just remove the loop and still leave lockshiels on the towel railas anextra bit of safety and alls well.

No, this one calls for a ABV in the installation manual. I am not a fitter by any means but I usually refer to the installation manual for any info. One assumes that it doesn't have an internal bypass. I know a lot of the cheaper ones don't.

The valves on the towel rail are of the fully adjustable type. TBH they look really nice. I've fitted similar before and couldn't find them then they happened to be the B&Q Tradepoint supplied ones. They've got a lovely feel to them. I was thinking of disabling those by drilling out the knurled hole and refitting the caps as a lockshield.

 

[mrlennie]

Why would it be best practice to fit at least 2 metres from the boiler if alot of combies have them in the box? confused!

 

[thewetspark]

If the customer doesn't want to pay for the alteration don't do it, leave the loop in and the last rad cold, it's their choice if you've explained it too them, just do the work you costed for.
I've done loads of "free" work over the years to make things "right" but you get no thanks and the bodgers still do the jobs cheaper than you and get away with it continuously. The guy fitting the boiler should have fitted an ABV but didn't, or better still put the rad controlling a roomstat on lockshields so the system shut down properly like it should with an interlock and not cycle until the timer shuts it down.

 

[thewetspark]

mrlennie.
Saw your post after I'd just posted mine. If the boiler has an internal bypass valve it'll be set to shut down pretty quick when the system temp is reached, may even be interlinked. If a boiler needs an external ABV it'll need to disipate a little heat while the system temp stat gets it shut down or it could start "kettling".

 

[Cornish Crofter]

UPDATE

The easiest thing to do to suit everyone's needs was done.

As was suggested on this thread, I simply changed the valves on the heated towel rail for lockshield valves and removed the loop.

I have advised the customer to get an ABV fitted as per the installation manual.

I was looking at a gate valve in a new replacement loop somewhere that could accomodate it. However when looking for a 15mm gate valve in my variety of plumbing bits I came accross a couple of chrome lockshield valves .

I think someone was trying to talk to me.

The whole job took less than an hour. I shut off the valves that were there, disconnected and removed the towel rail, drained that part of the system to clear the pipes of water then cut and capped off the loop at each end using ring solder end stops. After swapping the valves and tails over I refitted the towel rail, connected up the pipework I had disconnected to drain and refilled the system.

I have started with both valves on almost full. My reckoning is that the valves open full will be about as restrictive as the loop was. The towel rail is getting warmer, but the temperature is not brilliant. The whole system is plumbed in 15mm, mainly Hep 2o. This is despite it having about 15 rads. So I'm not surprised that the rads at the end of the run are taking time to warm up.

I would have liked to fit the ABV but feel that this is the best compromise. It gets the room warm enough for me to think about using tile adhesive and it sorts out the customer.

The lockshield valves replaced the non TRV adjustables that I had bought. I'll use these somewhere else. So really it only cost me an hours labour.

Thanks very much for all your input.

 

[mrlennie]

Ah I see I see so an internal ABV is different wiring of course nice one the wet spark. Will fit ABV's two metres from boiler .

 

[mrlennie]

UPDATE

The easiest thing to do to suit everyone's needs was done.

As was suggested on this thread, I simply changed the valves on the heated towel rail for lockshield valves and removed the loop.

I have advised the customer to get an ABV fitted as per the installation manual.

I was looking at a gate valve in a new replacement loop somewhere that could accomodate it. However when looking for a 15mm gate valve in my variety of plumbing bits I came accross a couple of chrome lockshield valves .

I think someone was trying to talk to me.

The whole job took less than an hour. I shut off the valves that were there, disconnected and removed the towel rail, drained that part of the system to clear the pipes of water then cut and capped off the loop at each end using ring solder end stops. After swapping the valves and tails over I refitted the towel rail, connected up the pipework I had disconnected to drain and refilled the system.

I have started with both valves on almost full. My reckoning is that the valves open full will be about as restrictive as the loop was. The towel rail is getting warmer, but the temperature is not brilliant. The whole system is plumbed in 15mm, mainly Hep 2o. This is despite it having about 15 rads. So I'm not surprised that the rads at the end of the run are taking time to warm up.

I would have liked to fit the ABV but feel that this is the best compromise. It gets the room warm enough for me to think about using tile adhesive and it sorts out the customer.

The lockshield valves replaced the non TRV adjustables that I had bought. I'll use these somewhere else. So really it only cost me an hours labour.

Thanks very much for all your input.

Well done dude don't be a walk over if you fixed everyones mistake to building regs you'd be in debt lol. Actually you'd be bankrupt.

 

[tackleburger]

What make and model of boiler is it? Have you checked to see if there is one already in the boiler?

 

[Cornish Crofter]

What make and model of boiler is it? Have you checked to see if there is one already in the boiler?

It is a Heatline Solaris, either 24pc or 30 pc - don't know which. Neither do I know if it has one.

However I have read the installation manual that the customer had, and it specifically states that an ABV should be fitted with bypass.

However, I was not there to fit an ABV but to technically leave the system as it was, so towel rail with lockshields now replace the bypass already there. It worked before so it should work now.

I know only too well the perils of leaving out a bypass. This happened with a boiler installation that I paid for. The fitter for some reason thought there was a bypass of some sort fitted. There wasn't. I had a knackered boiler and an angry tenant on my hands. Bypass valve went in PDQ at my insistance, which I paid for and he fitted. Boiler was fixed under warranty.

In this situation I knew there was a loop, which I just had to keep in one way or another.