Adding UFH as supplementary heating

[IanMK13]

I have a gas boiler for DHW and single zone heating (S-plan with TRVs on all radiators). Now I'm retired and my circulation isn't as good as it once was, I have problems in the colder months with cold feet - particularly on tiled or engineered wood panel flooring on the ground floor. I have been wondering whether I should take the opportunity of supplementing the radiators with UFH while replacing the flooring in these areas. I realise it's not ideal, but would I be able to get away with connecting to the existing radiator flow and return? Getting separate pipework back to the boiler would be out of the question.
Thanks for your advice.

 

[SimonG]

To be straight to the point, no.
1. No temp control of floor. Safety issue and potential for damaging floor coverings.
2. Pump wouldn't be man enough for the increased resistance through the loops.

Have a look at an overlay system. In the end it may be easier than you think to get pipes back to boiler. Should only need two 22mm pipes and cables from boiler to manifold location.

 

[IanMK13]

Hi SimonG. Thanks for your reply.
I suspect you have misunderstood my suggestion - I wasn't considering connecting the UFH pipe directly across the existing rad flow and return. I expected a manifold with pump, thermostat and controls. The problem in getting back to the boiler is there are two recently tiled (floor and wall) bathrooms between the boiler and affected rooms.
I'm not aware of overlay systems. Please could you give me a steer.

 

[SimonG]

I read it differently but can see what you are meaning now

I've added a link for nu heat overlay, but other manufacturers do it.

LoPro®Max underfloor heating

Ideal overlay or retrofit underfloor heating solution. LoPro®Max features high heat output & low height build-up, perfect for renovations & extensions.

www.nu-heat.co.uk

 

[EvilDrPorkChop]

Hi SimonG. Thanks for your reply.
I suspect you have misunderstood my suggestion - I wasn't considering connecting the UFH pipe directly across the existing rad flow and return. I expected a manifold with pump, thermostat and controls. The problem in getting back to the boiler is there are two recently tiled (floor and wall) bathrooms between the boiler and affected rooms.
I'm not aware of overlay systems. Please could you give me a steer.

In another word, No. It'll starve your rads of heat. Even this way. Needs to be a dedicated flow and return from the boiler, or at least tee'd off 22mms near the boiler.

 

[IanMK13]

Thanks, SimonG. Sorry I was not clearer to start with. The Nu-Heat product is a similar idea to the 15mm grooved panels I have looked at.
I realise that connection to the boiler is best and that not doing so will unbalance the rads (assuming the system is balanced now) and that the boiler temp & timer controls will override the UFH controls (does the manifold pump turn off if low inlet temperature?). Given that I only want something to supplement the rads and realise I won't get the normal full benefits, are there any potential problems I haven't considered?

Edit @EvilDrPorkChop - I think the distribution around the house (after the boiler zone valve) is either 15mm or 22mm with 10mm Tee'd to individual rads

 

[Murdoch]

Woollen carpets or mats is probably the least painful and cost effective solution.

Just saying

 

[EvilDrPorkChop]

I've done it before at the insistence of a customer who didn't want to run back to the boiler and was adamant it would work, advised him it wouldn't work properly or efficiently. It starved all the downstairs rads, ended up putting two new 22mm pipes back to boiler 5 years later.

For the cost of the overlay it's not worth doing it incorrect. As others have said you'd be better investing in other options or electric UFH if you just want floor temp warmer.

 

[Brambles]

Be a bit careful. There is a risk of making the house colder or extending the whole house heat up time, if you install a wet underfloor heating (UFH) system in the way in which you describe. The pumped UFH is probably the path of least resistance and will take the majority of the flow until it is up to temperature. If you encounter those conditions the only solution is to turn off the UFH ( which defeats the object of the investment).

A wet underfloor heating system is not cheap investment. If it cannot be installed to a properly worked out design, I would be very wary of proceeding