Vailant EcoTEC pro 28 - underfloor heating

21 Sep 2013
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West Midlands
United Kingdom
Hi everyone,

I am planning to replace radiators in two bedrooms with a water underfloor heating. The rest of the house will remain as is with radiators. The boiler is Vaillant EcoTEC pro 28.

The EcoTEC boiler has its own internal pump and what I always see in the underfloor heating setups is a pump connected to a manifold.

Now the question. Can I connect additional/external pump to the EcoTEC so that it starts when the boiler starts? Alternatively, do I need the additional pump at the manifold if there is already one in the boiler?

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Hi everyone,

Now the question. Can I connect additional/external pump to the EcoTEC so that it starts when the boiler starts?

Manifold circulator should be powered via UF zone valve (brown).

Alternatively, do I need the additional pump at the manifold if there is already one in the boiler?


Many thanks Steelmasons.

I have looked at the EcoTEC pro 28 papers and couldn't find the UF zone valve. Does it have any electrical contacts to connect the external manifold pump?

I'm sorry if I wasn't clear in my original post, but what I'm asking is the electrical connection for the manifold pump and this I would expect to be somewhere in the junction box/PCB.

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You don't seem to have done any research at all about UFH.

It needs to be timed and controlled separately from the rads.

It needs a separate motor valve, blending valve and pump!

Better to read it up!

Sorry, if I skipped a few items from description of the problem at hand.

The UFH that is going to be installed will have separate control, the question is that because there is this circulating pump and mixing valve at the manifold it has to switch on when the boiler switches on and sends hot water to the system.

There are single circuits UFH where the circulating pump is switched on and off by a temperature sensor in the mixing valve, .e. if the boiler supplies hot water to the system it reaches the mixing valve and the sensor then switches on the circulating pump on the UFH single circuit. When the water temperature drops (because the boiler stopped) then the sensor switches off the circulating pump.

However, for a multicircuit UFH with manifold, you're right, there is a manifold and a mixing valve plus the circulating pump. There is no temperature sensor in the mixing valve to switch on/off the circulating pump, it has to be switched on and off from the boiler. So, this is it, there is a 240V cable from the circulating pump and it has to go to the boiler. but the question remains - is the EcoTEC pro 28 designed to connect this circulating pump to its control circuit?

Hope I am now clear enough.

Also how do you plan to retrofit it upstairs?

I'd look at electric or not bother to be honest.
Well, this is the whole point. I want the circulating pump being switched on when the boiler switches on. The boiler is controlled by a room thermostat (the coldest room in the house). The whole house is on the same circuit. If the temperature in the room with thermostat drops below a threshold during time when we need heating the boiler switches on and that's it.

Thermostatic valves on radiators in all other rooms keep the temperature at levels we want. No problem with that.

Now, if I get rid of rads in two rooms and do the UFH via manifold supplied with the circulating pump on the same circuit I want the pump to start when the biler starts. Temperature in the two rooms with UFH will be controlled by electromechanic valve actuators on the manifold connected to room thermostats. This is it, simple. The only thing that bugs me is if I can connect the circulating pump to my existing boiler.

I thought I was clear about this.

Sounds like a complete botch of an idea. Ufh should be on its own independent zone when working with rads.


If you have a zone regulation unit then you just power it off a fused spur. It has no electrical connection to the boiler.
Amazing how someone can want to spend hundreds of pounds but has not understood anything about UFH.

A room with UFH can take up to TWO hours to warm up.

You need to separately time UFH zones so that it starts a couple of hours before the rad zones!

Id like to bet the floor wont even be up to temperature before the existing room stat shuts the boiler down, never mind the room.
Zone the ufh seperatley to the rads or don't bother putting in the pipes imho
Thanks everyone. This is all very informative and helpfull.

Two comments from my side to finish this off:

1) The fact that I asked these questions as part of my research before any work has started means that I may not know much about UFH, but it also means that I want to fill in the gaps. Taking this into account in responding would not be a bad think. I think this is what these fora are for.

2) I have asked a very specific question and didn't get the asnwer. But it is always easier to point someone else's lack of knowledge that demonstrate your own.

Anyway, now I know more than I knew a few days ago and this is what matter.

You had a perfect answer from the off.

You then got more information to guide you further with your research.

How you interpret that information is up to you. Do you want us to come and do the work for you?

The information you gave us was sketchy to say the least.

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