Drain down hot water pipe

[Harry Bloomfield]

The boilers pressure gauge has nothing whatsoever to do with the domestic hot water. It indicates the pressure in the sealed heating system.

You need a separate pressure gauge, which you can connect directly onto a mains pressure cold tap. The pressure measured, will vary, depending upon the height of the tap you check, above ground level.

The gauge on your boiler, only displays the water pressure in the sealed system of your radiators. That measured pressure, will vary, depending upon whether the water contained in your radiators is hot, or cold.

 

[TryAgain1]

As per terry changing to 22mm will make it worse

Ok. What sort of drain valve is best to install on 15mm hot/cold water pipe?

 

[TryAgain1]

You need a separate pressure gauge, which you can connect directly onto a mains pressure cold tap. The pressure measured, will vary, depending upon the height of the tap you check, above ground level.

The gauge on your boiler, only displays the water pressure in the sealed system of your radiators. That measured pressure, will vary, depending upon whether the water contained in your radiators is hot, or cold.

So a 15/22mm in line pressure gauge? What make/manufacturer do you recommend?

 

[foxhole]

So how are you measuring the 65degree hot water temp?Seems likely you are confusing central heating temp with hot water temp.

 

[TryAgain1]

You could fill the whole room with rockwool ,how is that going to result in water coming out the taps hotter than the " lukewarm" that you currently told us about ?
The boilers pressure gauge has nothing whatsoever to do with the domestic hot water. It indicates the pressure in the sealed heating system.

Said bathroom has no underfloor insulation and has a cold floor. Whilst I agree the exit hot water tap temperature won't change from insulating under the floor, the bathtub's heat will last longer with more insulation

 

[TryAgain1]

You could fill the whole room with rockwool ,how is that going to result in water coming out the taps hotter than the " lukewarm" that you currently told us about ?
The boilers pressure gauge has nothing whatsoever to do with the domestic hot water. It indicates the pressure in the sealed heating system.

The boiler has 2 displays one for hot water (tap) temperature the other for radiator temperature. The outlet temperature on both can be adjusted separately.

The insulation under the bathtub has no effect on the bath tap exit temperature however more insulation under the bathtub will retain heat both within the bathtub for longer.

 

[TryAgain1]

So how are you measuring the 65degree hot water temp?Seems likely you are confusing central heating temp with hot water temp.

The boiler has 2 separate controls for heating radiator and heating hot water. Not confusing anything.

 

[foxhole]

The boiler has 2 separate controls for heating radiator and heating hot water. Not confusing anything.

Separate controls but no display for hot water ?, so how are you assessing that temp ?

 

[TryAgain1]

Separate controls but no display for hot water ?, so how are you assessing that temp ?

The same display is used for bot hot water and for radiator temperature, the readings switch between both. So if you turn up the radiator temp by 1 setting the display will show rad temp then if you immediately change the hot water temp the display will show hot water temp.

 

[foxhole]

The same display is used for bot hot water and for radiator temperature, the readings switch between both. So if you turn up the radiator temp by 1 setting the display will show rad temp then if you immediately change the hot water temp the display will show hot water temp.

Have you confirmed the hot water temp with a thermometer ?

 

[TryAgain1]

Have you confirmed the hot water temp with a thermometer ?

Nope. The boiler manual backs what I have said.

Here is a list of the two components I need to make a 22mm x 22mm x 15mm drain valve on the hot water outlet about 0.5m from the boiler. I would put 22mm pipe clips either side of this valve

1. 22mm x 22mm x 15mm tee: https://www.screwfix.com/p/flomasta...mm/25631#product_additional_details_container
2. 15mm drain valve: https://www.screwfix.com/p/flomasta...mm/658fa#product_additional_details_container

The 15mm drain valve would be compression fitted into the 15mm tee.

I would use PTFE tape and copper olives on all threads

Does this sound about right?