Rearranging pipework any issues?

[Madrab]

Technically you don't need an autobypass if at least one of the rads doesn't have a TRV on it.

By fitting an autobypass all that's being achieved is there will always be at least a minimum flow through the boiler on pump overrun. In other words when the thermostat has been satisfied and the boiler stops firing but the pump runs on to dispell the latent heat in the HEX. As long as one rad is still open there will always be flow,

 

[kevinsmbuk]

Technically you don't need an autobypass if at least one of the rads doesn't have a TRV on it.

By fitting an autobypass all that's being achieved is there will always be at least a minimum flow through the boiler on pump overrun. In other words when the thermostat has been satisfied and the boiler stops firing but the pump runs on to dispell the latent heat in the HEX. As long as one rad is still open there will always be flow,

Thanks for the reply, this is the original issue I am having though. So the rad that doesn't have the TRV on is in the hallway. This heats up with the hot water. In the kitchen the pipework most accessible for a kitchen/dining room radiator (and that needs a bit of rearranging for the new kitchen) is tee'ing off this run. This means the kitchen radiator which is quite hefty will also heat up with the hallway radiator with the hot water. You guys were coming up with ways to avoid that needing to happen.

 

[Madrab]

Ahhh... yup ....

The autobypass needs to be before the valve and then plumber into the return, ideally after the last return from the CH/HW

 

[kevinsmbuk]

Ahhh... yup ....

The autobypass needs to be before the valve and then plumber into the return, ideally after the last return from the CH/HW

Is this something I need a plumber for? I have done quite alot of other work on the system Inc draining fitting three radiators with copper pipework/soldering. But I wouldn't say I'm overly familiar with all parts of this system

 

[Madrab]

Not especially so .... if you are handy with pipework. You need to tee in after the pump but before the inlet to the valve. Then you just need to follow the return from the boiler back and find a suitable place to tee into the pipework, the autobypass valve is then fitted to that pipe run. You can use compression if getting the main pipework drained and dry isn't easy.

There are ideals like you want to obtain as much pipe length from the boiler as possible, that speeds up the heat draw from the boiler's HEX but as long as it supplies the min flow through the boiler, that's the target.

 

[kevinsmbuk]

Not especially so .... if you are handy with pipework. You need to tee in after the pump but before the inlet to the valve. Then you just need to follow the return from the boiler back and find a suitable place to tee into the pipework, the autobypass valve is then fitted to that pipe run. You can use compression if getting the main pipework drained and dry isn't easy.

There are ideals like you want to obtain as much pipe length from the boiler as possible, that speeds up the heat draw from the boiler's HEX but as long as it supplies the min flow through the boiler, that's the target.

OK that makes sense. Can you give me an idea of what autobypass valve I need. Also what is the ideal length of pipework that I need to run from the initial t, to the valve then to the return?

It's a baxi eco blue system boiler

 

[Madrab]

As far as the valve is concerned then pay a bit extra for a quality valve, can go wrong with Honeywell IMO

The pipe length to the valve isn't that important as it wouldn't flow until the valve opens anyway but it all really depends on the length of line from where the tee will be before the valve and where you can tee into the return. From the pics it looks like the pump is pretty close to the boiler so the run wouldn't be that long, can't really see. So you would probably want to artificially extend the length of the pipe back to the return before the boiler. I would keep the pipe exposed too as it will act as a heat emitter increasing the heat draw from the HEX.

 

[kevinsmbuk]

As far as the valve is concerned then pay a bit extra for a quality valve, can go wrong with Honeywell IMO

The pipe length to the valve isn't that important as it wouldn't flow until the valve opens anyway but it all really depends on the length of line from where the tee will be before the valve and where you can tee into the return. From the pics it looks like the pump is pretty close to the boiler so the run wouldn't be that long, can't really see. So you would probably want to artificially extend the length of the pipe back to the return before the boiler. I would keep the pipe exposed too as it will act as a heat emitter increasing the heat draw from the HEX.

OK so am I right in thinking it would be something like this (obv return pipework would look better!) blue is the bypass valve.

Is there any regulation restrictions to this, obv this line will be hot? So does the run have to be placed out the way

Also in order to drain to work on it, presume drain the system, then, use the drain cock on the boiler?

 

[Hugh Jaleak]

It wont be hotter than anything else nearby, probably best option would be to redo the section from the pump to Valve, using a Tee instead of a bend, then fit your Bypass at a suitable point, before going back to couple into the return at the easiest point. Any low points will need a Drain off, so if this section ends up lower than the boiler drain, for what it costs, put a drain off in it for future needs.

 

[Madrab]

All you really need to do is de-pressurise and empty the pipework you are cutting into, hence the use of compression as it wouldn't necessarily need to be soldered. The pump could be isolated and the only other pipework that would need to be drained is the pipework above the connections, which would be the B port to HW.

The downwards connection will be to the CH and as long as the rads are nice and watertight then the water loss would be minimal. Don't see a need to drain the whole system.

 

[kevinsmbuk]

So I have had a plumber round to look at this as to be honest I have had so much other work to do in the house I need help. He said that it's hard to see without looking at the whole system but he is saying that the solution of the autobypass would not work, he said the rad has been incorrectly plumbed into the primaries but we can get TRV for both the hallway rad and the new rad and the system will be fine.

I'm a bit confused as I know you guys know what your talking about and the plumber was knowledgeable aswell!

 

[Hugh Jaleak]

TRV's to me would be a get out, although that would avoid more complicated pipework alterations, it would never be an ideal solution in my book. Basically I think he's suggesting using TRV's which then should shut down when the house is warm enough not to need the output from those Rads and prevent them from stealing flow from the cylinder.

Ultimately I think it's down to a choice between what you want and what you want to pay for. To alter the system to plumb it correctly would be more expensive and time consuming, but would ensure all the Rads only heat up when heating is required, (and given Gas Price increases, precise control of heating is becoming more of an issue, understandably). Fitting TRV's should help prevent these rads heating at other times when HW only is selected, but there is no guarantee it would solve the issue completely and you could find these rads getting hot when you dont need them too, ultimately wasting heat and the associated gas used to produce that heat.