A house we are considering buying has wet underfloor heating connected to an oil fired boiler.
Said house was built in 2003.
Q1. As heat pump outputs are at a lower temperature, is there likely to be sufficient heat output from the wet UF heating if I switch from oil fired boiler to heat pump feeding the UF piping?
Q2. An estate agent told me that UF heating tends to start developing faults past around 20 years old. Anyone heard of this?
Thanks
Our wet U/F heating is maybe 30 years old and is fine. We flushed it through about 7 or 8 years ago.
In the other half of house we have heat pump with wet U/F heating which works fine. It takes 24 hours to heat up if you go away in cold weather tho”.
I switched from an oil fired boiler to a heat pump, I have underfloor heating in half of my (old) house and it is fabulous. A gazillion times better than my ofb.
What are the main benefits Vero apart from predictable fuel cost and environmental? Assume UFH was connected to oil burner previously. Is the warm up time any longer?
Must ask seller about this but isn’t it only needed when there are steel components like radiators?
Yes the UFH was connected to the ofb, but the warmup time was longer than with the heat pump, it took ages to warm up mainly because my house is quite long so even going across the courtyard underground then pipes had some way to go and the boiler wasn’t as reactive or efficient as the heat pump. The thermostats were set to the same temperatures etc. it is lovely in that part of the house in winter - it’s ok in the rest where there are radiators but I infinitely prefer the UFH. I love the heat pump.
I have another question. I’ve been told a vide sanitaire is important in areas like the Cause de Quercy where houses are built predominently on rock. They isolate the property from damp. I’m referring to modern houses.
I know they make life a lot easier for inspecting/installing various services.
Any views?
Whilst the crawl space allows access to some services etc its also a big source of heat loss as it has to have ventilation. If considering UFH considerable insulation should be installed with a breather membrane. I have to renue our underfloor insulation as the original has failed after 25y. I would look at removing the suspended floor in my next house if it has one and filling with shale and thick insulation.
Moving forward some months we’ve been enjoying the oil fired underfloor heating. Rather strangely it has just one thermostat for all seven loops and that’s in (what for ease we call ) the living space. It’s a combined kitchen/dining/living area. If we want the log fire lit then of course the rest of the house cools. Next year I hope to get a heat pump fitted. More immediately I’m looking at smartening up the controls with a Danfoss Icon 2 system with even more intelligence from Home Assistant. I’ve found wireless Icon 2 room stats at around half the price of French and German sellers. Waiting to see whether the Danish retailer will ship them. Danfoss is of course a Danish company. I don’t mind paying extra here but this is silly. Currently the UFH is very difficult to set to the right temperature and the bedrooms are hotter than the living space. I’m adjusting the manual valves but of course the big slab has a lot of latency. I’ve read a heat pump with modulating output will pair perfectly. We’ve yet to submit a French tax return. Wondering at what stage I can try to get state help with change to to HP. Also have plans for solar. I think it will help even in winter down here in the Lot.
Yes Michael you need zone separation by the sound of it and home energy monitor seems a good platform. Not sure about investing in new equipment for control this year that could be obsolete when you fit a heat pump next year. The control packages should ideally come from the heat pump company so it all speaks the same language.
Investment is about 100 Euros for the UF heating actuators which I would need anyway for any system plus about 60 Euros for a couple of wireless relay units which I can reuse for something else. Control is Home Assistant using thermometers which I use already. I’m learning how to use Node Red to simplify the programming.
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AHH not so bad then. What is your current flow temperature out of interest?
Around 35C. I know that when I have a pompe chaleur water flow temperature regulation will be part of the control set up.
I’ve been surprised by the difference to overnight temperatures some sunshine in the day makes.
I previously manually adjusted the flow to the bedrooms which were too warm and the last few cloudy days the temperature has fallen overnight compared with previous days.
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It’s an interesting toy isn’t it. I have been installing more radiators with the move towards lower flow temperature next year when I revamp the system. The weather compensation sensor should be a big money saver as it will take over the modulation of the new boiler. When my wife is in hospital the floors are coming up for much better insulation to be fitted. I would go to a heat pump but not until the electricity prices in the UK reduce and that isn’t likely to happen until a major shift in the government.