Why do you need an extra pump on UFH?

[samtheman1k]

I'm hoping that someone can answer this? I wish to put UFH in my conservatory, since it has already been built (many years ago) and has a concrete floor, I'm going to use the polyplumb overlay system, with insulation below and tiles on top.

The boiler (gas) is also in the conservatory. Why do I need an extra pump? I'm going to put a mixer valve, so why the extra pump? Surely if the whole system is balanced correctly, then the mixer valve will ensure that water will flow through the output? [/url]

 

[Agile]

The simple answer is that you dont! In fact in europe they often use the boiler to control the UFH directly.

In the UK its been the custom to use a boiler giving a higher temperature flow and a circulating pump and blending valve. Since the boiler only pumps hot water then you need a pump to circulate the UFH water and the blending valve add hot water as required.

I would suggest that a DIYer takes professional advice if installing UFH as it becomes an expensive mistake if anything is done wrong.

Tony