hot water tank and pressure relief valve

[grantnet]

Hi,I am installing an "aarow stratford t70"multifuel stove.In the installation book it states that the system requires a pressure/temperature relief valve discharging via a tundish to the outside.The system is an indirect and the only hot water tanks i can find have 5 tappings(plus immersion heater) How do i fit the PRV without a tapping.Any ideas would be very welcome

 

[ChrisR]

A ptrv would only normally be used in a sealed system. Is either your boiler/heating, or HW system, sealed?

 

[grantnet]

Thanks for the info ChrisR but I have checked the installation instructions and it definately shows a open pipe vent to the header tank and also a self setting temp/pressure release valve installed at the top of the hot water tank.I assume it is in case of a power failure(no pump)and the fire overheating.

 

[ChrisR]

I see - now I've found the correct rather odd spelling!
http://www.aarrowfires.com/pdf/stratfordtf.pdf Page 29.

They seem to be a bit muddling between the primary (stove) circuit and the hot water in the cylinder.
I think you'd better call them! I've not seen a cylinder with a tapping where they indicate. An Essex flange wouldna take the temperature, cap'n. I suppose you could use a Warix flange screwed into the centre top of the cylinder (HW out goes off sideways). Not sure I entirely see the logic of a "normal" ptrv on the hw cylinder though, as it's open vented. They open at about 90 degrees, and the water could only get to 100. Could you tell the difference?!!
They're set to several bar pressure, too, which the cylinder wouldn't stand ....

Can't help wondering if it's a case of a manufacturer covering its backside. Like the hob manufacturers who insist on a "linked" extractor which comes on as soon as the hob is operated - but they don't give you a switch to connect it .....

There may be special valves for these stoves I know nothing about though.
We used to have to use these things
http://www.bes.co.uk/products/graphics/7512.gif
near boilers, but they're carp really, as they always leak sooner or later, and you have no idea what pressure they're set to: £1.20 !

 

[grantnet]

Hi ChrisR.Sorry about misleading you with the aarrow spelling but thanks for persisting!I have looked up "warix flange and also came up with "surrey"/"essex"flange. The idea looks good but will the ptrv fit into any of these?(I have heard of essex and surrey but where the devil is warix)