Flow pipe to Rad hot

[tatters40]

Hi Guys

Bit of assistance please

I'm fairly decent with most DIY but trying to get head around the following....

Heating off (Hot water on) isolated Rad in my lads room at the TRV and Lockshield.
Started draining rad in preparation for removal (decorating) immediately pipe on flow side becomes very hot to touch. The carpet in my daughters room is also warm suggesting the flow pipe to her rad is also hot with the heating off.

Struggling to understand why hot water is finding its way to the TRV with the Heating off.

2 way valve issue? (even though no pump)

Hope you can help

 

[terryplumb]

Are you stating that you do not have a pump ?
More details of your set up needed methinks !!

 

[CBW]

Could it be Reverse circulation?

 

[tatters40]

Hi guys, sorry original post lacked a bit of info.
Fairly old open vented system with tank in the loft and cylinder in the airing cupboard, Normal 3 speed pump and zone valve adjacent the Boiler.

Heating had been off for some time now.

Basically isolated rad at TRV/Lockshield to drain rad for removal for decorating

The TRV won't shut down totally and weeps slightly (which i'll replace) but on opening and closing the valve very slightly into a bucket i noticed the pipe getting very hot right up to the TRV. Please note Heating is off but Hot Water is on.

As mentioned previously it is possible to feel warmth underfoot in my daughters bedroom suggesting pipes up to her rad are hot (the rad isn't)

Bit confused tbh

 

[terryplumb]

Is the " zone valve" a 3 port valve ? 3 pipes going into it ? If so ,that's the problem !

 

[tatters40]

Hi Terry

I'll check as not looked mate and thanks for the message, can you explain potential issue if 3.

 

[terryplumb]

3 port valve can divert water from boiler to either the cylinder ( to give domestic hot water) ,or to radiators ,or to both. Depending on what you select on your programmer. When in the domestic hot water position ,no boiler water should get to radiators. If the valve doesn't fully close , the result is as you describe.
Replace the valve.

 

[tatters40]

Terry - top man