Central heating installation HELP!

[Matthewh95]

Good afternoon all,

I am soon to have a new combi boiler fitted to provide central heating and hot water (currently just have an old hot water boiler).

I am in the process of fitting my central heating system pipe work, and I am hoping for some advice. I have drawn up a picture below of what I intend the central heating system to look like, please can you comment on whether it is correct?

My main concerns are as follows:
Can I tee my main flow and return just below the boiler to go each way? The boiler is in the centre of the house and therefore will need to provide hot water in both directions. Will this cause any issues with the flow rates?

Secondly, I have TRVs for all of the radiators. Do I need to leave one open so that the system can regulate pressure? Or do I need to cross connect flow and return with some sort of bypass valve? Any help is greatly appreciated.

Thirdly, any other issues with what I have drawn up below?

Thank you for your time reading this, and thanks in advance for your help

 

[kidgreen61]

Looks ok to me, but choose one rad to act as a bypass by fitting lockshield valves to both ends, and leave them open, this is usually the rasd nearest room stat.

 

[Matthewh95]

Thanks @kidgreen61, I appreciate you taking the time to reply

 

[oldbuffer]

1. Depending on what boiler you get it may have an internally fitted automatic bypass. This may well be adequate, depending on system size.
2. If not fitted, or not adequate, you could fit an automatic bypass between flow and return. Locate it to give a decent length of pipework to allow the water to cool if all TRVs shut.
3. If you are piping in plastic, remember that most boilers require the metre closes to the boiler to be in copper. Check the instructions for your boiler.
4. Your scheme looks fine. You'd do well to fit the spine (flow and return) in 22mm pipe, with 15 mm off the spine to each radiator. You could go larger on the spine if you are thinking of a heat pump in the future.

 

[Matthewh95]

@oldbuffer thats a great comprehensive response!

The new boiler is a top of the line Ideal Maxi combi, (can’t remember the name of the top of my head) so pretty confident that it’ll have a built in bypass based on what you’ve said.

I’ve already begun plumbing the main run in 22mm pipe, albeit it plastic. I’m going to come up the wall to each rad and the boiler itself in copper, so that should be that covered.

Thanks for your time and help

 

[muggles]

Never heard "top of the line" and 'Ideal" in the same sentence before. The Vogue is OK I suppose, the Logic is definitely well below average and 16 months worth of production are currently subject to a safety recall. They do both have an internal bypass but weirdly the installation instructions state that an external one should be fitted as well.

 

[DP]

currently just have an old hot water boiler

Having a boiler heat water in a cylinder is not an old system.

Combi is a package deal that often is not user friendly.

If existing system is open vented ( suspect it is), combi will find the tiniest leak or a weep in the system

 

[jurassic sparkk]

If existing system is open vented ( suspect it is), combi will find the tiniest leak or a weep in the system

Not always the case.

 

[DP]

Not always the case.

Agreed, but if the boiler is aged Potterton Kingfisher or Ideal E type, encountering a radiator valve that will hold back 1.5 bar pressure is like winning a lottery