Central heating layout design

[Niel A. Farrow]

Hi, I'm redesigning my central heating, changing from an old oil boiler to gas and installing a new HWT.

Currently, the boiler is at one end of my long end semi. The pipes split next to the boiler, one set going upstairs and travelling to the front of the house to serve the upstairs rads, and the same downstairs.

I would like to move the HWT to the landing in the middle of the house with the boiler above it in the attic (changing to fully pumped).

My question is; With this arrangement the pipe from the boiler will split for upstairs and downstairs rads, but instead of being a straight run they will both have T-pieces near the boiler for the pipes runs to the rads at the front and rear of the house. Will this work and be efficient.

Thank you,

Neil

[Christian McArdle]

Yes. As the splits will be near the boiler, take the time to install 2 port valves for the upstairs and downstairs circuits and run on a Honeywell 'S' plan. This way, you can have a seperate programmer and room thermostat for each floor, meaning you don't wastefully heat your bedrooms during the day.

As you have additional splits for the front and rear, you could even put valves on these, giving four zones for even better control. It would depend on exactly which rooms were served to decide if this would be beneficial.

Ensure every room with a wall thermostat doesn't have a TRV on the radiators. You'll need to balance the system properly, ensuring that rooms with TRVs heat up quicker than rooms with wall thermostats. This will ensure that the boiler and zone valve is not turned off when TRVed rooms still need heat.

Christian.

[Andy Hall]

I had a very similar issue, Neil.

It will certainly work and there are a few things that you can do to improve the flow conditions.

- If possible, and the fittings allow, do the connections to the boiler in 28mm rather than 22mm.

- It is best to make swept bends with a pipe bender to reduce the resistance. If you don't have a bender for 28mm, a good substitute is to use two obtuse bends with a short length of pipe between them.

- For the tees I used 28mm types which instead of being completely angular are made with a swept bend each way. I then ran about a metre of 28mm pipe on each leg before reducing down to 22mm. I used 28mm zone valves.

The key thing is to avoid using sharp bends wherever you can. If you have a choice of pump, a Grundfos Alpha is useful because it has adjustment but also adjusts output automatically to the pressure resistance

.andy

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