confused.....

[secret squirrel]

Has anyone an insight into this please:

I replaced a radiator in a bathroom, open vented system, 3 port valve, boiler, cylinder and controls upstairs.

All the radiators in the house are fitted with trv's (I know this shouldn't be the case) underneath the bathroom rad is a by pass, a length of 15mm tube connecting flow and return on an isolator.

The problem is, when the heating is first turned on the new rad gets really hot and is then turned off by the customer on the trv, (elderly cust who turns it on or off and doesn't let the trv do its job). When the room cools to below acceptable the trv turned on and the rad refuses to get hot and refuses to get hot until the heating is turned on again the next day.

I went back yesterday and opened the engineers valve fully. Maybe, I've restricted the flow too much but why does it work at all!

The confusion for me is the radiator works when the system is turned on, maybe the customer doesn't give it enough time. I thought the pump is playing up but again the rad gets hot when first on!

So, any insights please.

[SimonJohns]

Trv sticking shut. Try swapping with ls. May say on the box bi-directional. But this isnt always the case

Btw. Have you balanced the system correctly

[secret squirrel]

No, not balanced system just changed one rad for another same size.

I did think trv but being a new one! every thing points to that though....

[APPlumbing]

Bathroom rad on the heating circuit and not on the hot water circuit? Is it an old trv?
As Simon says does sound like a balancing issue.

[secret squirrel]

Bathroom rad on the heating circuit and not on the hot water circuit? Is it an old trv?
As Simon says does sound like a balancing issue.

TRV is new, I will probably have to go back and play with the balancing, pin on trv didn't appear stuck,

Heating circuit or hot water circuit thats very interesting, if that is the case the previous rad would have done the same which would have held the heat for longer,

That makes sense, h/w and heating come on in the morning rad gets red hot, heating comes on during the day rad stays off.

[kay-jay]

its not unusual to find a rad on the hw. the bypass should be on the heating circ tho

[secret squirrel]

I think I couldn't see the wood for the trees, I had dismissed a balance issue because both rads were the same size,

I'm almost sure thinking about it the rad is on the heating circuit but this will need checking. The amount of times I've explained to customers about the h/w circuit and the bathroom rad. The problem is the cust hadn't said this was an issue before and I never checked!

And because the bypass is on this rad I'd have thought this would be a heating circuit, after all its been there years..

Balancing it is then....

BUT why does it heat up initially and then not, presuming its heating circuit etc. I can't think of a reason why,