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Underfloor heating and combi boiler service

Postby JoshEDD94 » Mon Nov 02, 2020 7:15 pm

Hi All

Feel a bit cheeky openly asking for free advice, thanks in advance.

Moved into a new build approx 2 yrs ago. They have electric (Fiamma) combi boilers installed from

They also have Ambiente/Heatmiser UFH heating system, operated from combi boiler.

Over the two years lots of flats in the block have had problems, from pressure dropping consistently, pumps seizing to leaky PRVs. We're in a hard water area, and we've had lots of different advice. Some say lack of inhibitor is an issue, some say lack of filters is an issue, some say pressure loss is normal.

The company above offer a servicing regime, @£120, but I wanted to get a couple of points clear before I begin.

- When you top up the combi boiler pressure, this dilutes inhibitor, right?
- The dilution of inhibitor would also dilute the underfloor heating inhibitor, right? (some people have said they are separate filling loops, some say they are the same)
- What should I be looking for in a service? The electric boiler doesn't have a flue etc - and I don't believe normal services include any re-dosing of inhibitor, so is there any value in a service (I've recently had an electrician check all electrical connections)
- PRV and AOVs have been a common fault in the building block - anything I can do to prevent this failure?
- Do I need to be bleeding the UFH system at all, or is that included in a service?

I know that's lots of questions, sorry! I've made every effort to read manuals, get advice from the different trades people the developer has sent, but it can be hard to work out what is a sales pitch on behalf of the developer, and what is true. I.e. we were told they were service free boilers, but when faults started happening they refused to help because they said we didn't get them serviced - doh!
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Simply Build It

Postby ericmark » Sun Nov 15, 2020 10:51 am

It seems an odd set up, main reason for a boiler is gas or oil is cheaper than electric, and if using electric all you really need a "boiler" for is domestic hot water, in the main it would be direct, except when wanting to use off peak electric.

To use a so called storage radiator has been a failure because at the temperature of the bricks, it can't be turned off, you want some thing which can store the energy with very little escaping for at least 24 hours, so you can on a warm day turn the heating off, and the well insulated water storage tank is one way of storing energy. Down side is they tend to be large.

The floor will store energy, but like the storage radiator hard to turn off, so it does give one a warm floor, but control is the problem. When the sun comes out if can heat rooms rapid, and the heating needs to be able to respond just as quickly to stop heating the home, so it does not over heat.

I simply can't see how a combi boiler using electric rather than gas or oil has a place in any home, if not using off peak power why not a simple convection heater in each room, and a under sink heater and electric shower, I am clearly missing some thing.
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