Silly central heating radiator question

[Craig-SM]

Removed the old knackered radiators from the kitchen a couple of months ago whilst we’ve been doing work in there. One had a TRV fitted and pipe work was marked up for when the new one to is fitted.

The other radiator just had lock shields fitted on both ends. Would I be correct in thinking the pipe closet to the combi boiler, a couple of metres away, would be the feed pipe to fit the TRV to?

If not what is the simplest way to find out which is the feed pipe, both currently capped off?

 

[gaz1]

run central heating so the feed pipe are warm/hot then use a funnel type thing and run it into a bowl ( hint use a milk bottle to fire into )

turn on the valve gently and slight drain the system it wont be much but it will allow the heat to come through the pipe so you know which is feed

otherwise its trace the pipes to find the feed pipe but you cant always do that

a note here some feed pipes are actually the return feeds so they wont become hot if you only slightly fire the central heating system

you dont need long when you fire it 1-2 mins is more than ample enough to get the feeds red hot but wont allow the hot to come back through the return pipe

after that just top the system up

 

[Kayos]

Most, if not all, modern trvs are bi directional

 

[brightspark]

Most, if not all, modern trvs are bi directional

correct so it dont matter

 

[dobbslc]

Would not the rad with two lock shield valves be the bypass for the boiler to prevent overheating if/when all the others shut down?

 

[Craig-SM]

Would not the rad with two lock shield valves be the bypass for the boiler to prevent overheating if/when all the others shut down?

Whoo! That is beyond my comprehension. I thought the combi boiler would prevent overheating by cutting off the flame when the thermostat detected it was at the correct level

 

[Morrisman]

Whoo! That is beyond my comprehension. I thought the combi boiler would prevent overheating by cutting off the flame when the thermostat detected it was at the correct level

I thought all systems had one rad that was permanently on/open for just that purpose?

 

[Seadog]

Don't current regs.on new installations say that all rads need a trv, so can't be used as a bypass, and a separate bypass valve should be positioned at least 2 metres from the boiler with copper up to that point?

 

[Robotstar5]

I thought all systems had one rad that was permanently on/open for just that purpose?

I thought so too, in our case it's the rad in the bathroom.

 

[Kayos]

Don't current regs.on new installations say that all rads need a trv, so can't be used as a bypass, and a separate bypass valve should be positioned at least 2 metres from the boiler with copper up to that point?

Most combis have said that for 15+ years

 

[gaz1]

i always use the bathroom one as that close rad can rob and send heat back to the boiler fast therefore not heating up the house properly

as goes for the trv valve yes they say it can be used on both sides just one small thing its on the cold side so the room actually is warmer when it shuts off whilst on the feed side it can shut off just before the room is fully heated

which way is better pref the feed side

 

[Seadog]

as goes for the trv valve yes they say it can be used on both sides just one small thing its on the cold side so the room actually is warmer when it shuts off whilst on the feed side it can shut off just before the room is fully heated

That makes no sense.

 

[gaz1]

look at your valves and picture one on either side

when the water feeds into the rad it warms up the right side as it heats up and then radiates the heat outwards the return side is always colder

when the room warms up the heated side closes down earlier whilst the coldest side takes longer to warm up

if you have a trv valve pointed away from the rad it takes longer for the trv to heat up and shutting down the rad

 

[Pigeon_Droppings2]

I thought most trv valves these days are bi-directional so can be fitted on either side? I seem to remember the bi-directional ones have a double ended arrow stamped on the body of the valve.

But as above...check the bypass situation first before fitting. In our house the bypass is the towel rail for example.

 

[Seadog]

look at your valves and picture one on either side

when the water feeds into the rad it warms up the right side as it heats up and then radiates the heat outwards the return side is always colder

when the room warms up the heated side closes down earlier whilst the coldest side takes longer to warm up

if you have a trv valve pointed away from the rad it takes longer for the trv to heat up and shutting down the rad

Isn't the air temperagure the trigger?

 

[Kayos]

Isn't the air temperagure the trigger?

For a TRV, yes

Water temp doesn't affect it

 

[Mark 5]

Don't current regs.on new installations say that all rads need a trv, so can't be used as a bypass, and a separate bypass valve should be positioned at least 2 metres from the boiler with copper up to that point?

No not as far as I'm aware, current regs state all new wet systems must have TRVs fitted except the room where a room stat' is fitted, ( which is also a requirement ), to act as a bypass

Bath towel rails can, are used as the bypass, so standard valves fitted either end but this is not such a good idea in many cases imo.

 

[brightspark]

I thought so too, in our case it's the rad in the bathroom.

mines a conventional boiler and a y plan valve shower room and bathroom just open and shut valves the rest thermostatics