Fridihem,

You are right, setting up and commissioning is included in the price. Before my last payment in December there will be a final visit to check everything is working correctly.

I am the cause of the problem. I like to know what each parameter means and what is the best value for it to be set to. As I said, Dominique has not installed a Nibe system before, so we are learning together. I am very happy with this situation, but of course if Dominique had been experienced with Nibe, that would have been even better.

Your neighbour had an excellent experience, I think it is partly due to heat pump installation being a well understood and mature technology in Sweden. It is not the same in France and the UK. They are behind Sweden in heat pump installations especially the UK.

topher

I'm guessing we live in roughly the same part of France and having installed ASHP + UFH in 2007 I've been following your thread with interest and look forward to your first-winter reports to see how the two systems compare in similar climates. Have you been able to tap into the various grants/tax breaks ?

Hi topher

I'm in S.E.Vienne so our winters have a little more bite and you get a bit more sun, otherwise comparable.

Yes the resistance does kick in when it gets below -5 but the ASHP copes well, internal temps maintain the set 19 degrees (I set the thermostat to read a degree higher but don't tell Mrs. C) and the insulation is far from finished so I expect an improvement in overall performance come the end of the refurb when I'll also have a 10kw woodstove for back-up. The ASHP/UFH in cooling mode is a boon in summer but I'm looking at another way to cool - new thread in pipeline.

I'm a fonctionnaire and my kids were born here - being in the system had its rewards re the rebates.

Bonne continuation

Canute

Pic 1. March 2010. This is the water diviner looking for sources. He found two places. The bore holes were drilled at the points he found. He was accurate. He cost 65 euros.

Pic 3. May 2010. The boring machine towing the air compressor to the boring site.

Pic 5. May 2010. Lowering the pipes into the first borehole. The pipes are filled with water to make them heaver. They have a cast iron weight in a plastic torpedo shaped sheath to assist their descent into the 100 meter deep hole. There are four pipes per bore hole. Each pair has a U-shaped joint where they are attached to the weight. This gives two closed loops per bore hole.

Pic 7. August 2010. Pipes about to be placed in the trench. The pipes are very stiff and difficult to bend. The soil keeps them in place.

Pic 9. August 2010. My wrecked garden. The black pipe you can see is to add water to the bore hole if it becomes dry. This helps the heat conduction from the ground to the circulating liquid in the pipes. It does not mix of course. Very cheap to do. Seems a good insurance policy. Later on it was placed neatly under a small inspection cover.

23 October 2010. Report 12.
On Wednesday 20 October I installed a Kw/h meter and put the heat pump on. It was the first time it had been used to heat the house. It worked fine and brought the house up to 19 as set on the thermostat. I spent some time trying to understand all the different parameters that could be adjusted. I have a lot more to learn.

Everything was fine until Friday, when I noticed that the pressure in the primary (bore hole) circuit had dropped to about 0.2 bar. Previously it had been solid at about 1.5 bar. I opened the inspection cover where all the bore hole pipes are joined to a manifold. If you look back, you will see the picture before the cover was constructed. There were two small pools of red liquid - the manifold was leaking. I told the installer and he said that it was probably caused by the low temperature on the return side. When the heat pump is running the supply side is 9 to 11 degrees, and the return can be minus 2 degrees. It makes me concerned about the leak security of the manifold. In normal operation the temperature will vary from about +11 to - 2 degrees, and if this change is sufficient to provoke a leak, then is this going to be a continual problem?

I have seen a special manifold designed for this application. It has plastic pipe parts with electric resistance heaters which are used to melt the female socket to the inserted pipe. It would seem to give a much more secure connection. With 20:20 hindsight perhaps I should have insisted on one of these. Any one got information to add? It would be very interesting to hear about your experience.

This Saturday morning the heat pump had shut down by itself. The alarm help screen said that insufficient primary circulation was available to work the heat pump. Last night I could hear slight noise of air in the system. I await the arrival of Dominique on Monday to fix the problem.

Boo hisssssssss...

What a nuisance. Still, better now than mid-Jan I guess.

Thanks for the warts-n-all reporting. Very useful to know.

Rgds

Damon

My mum's parents had night storage heaters.

About 1/3rd of UK domestic electricity is still supplied on an Economy 7 tariff I think, though, so there must be plenty still out there... Or maybe one very very big one? B^>

Rgds

Damon

Topher,
why do you have a 3 phase supply? I assume they are not standard for homes in France? Do you have an occupation and/or hobby, e.g. welding, that uses 3 phase equipment?
If I were to install 3 phase in a workshop/ studio for my daughter's architectural glass business, would this mean I would have a choice of more efficient heat pumps or just larger models?
I think that Nibe do heat recovery heat pumps which may be relevant to a workshop with kilns. More research needed!

SteamyTea,

I should have thought first. I have been to Goonhilly and can understand why you have night storage heaters. My Mum had one, and had the same relationship with it as you do with yours.


Docmartin,

Most houses here are single phase. I believe the following is the explanation for the three phase. In 1985, when the house was restored, it was calculated (wrongly) that 9 Kw of heating was needed. In France circulation of warm water underfloor has always been popular and fortunately it was installed. Taking 9 Kw from a single phase supply is a large load, three phase is better able to supply such a demand. As it turns out, 9 Kw is not enough. When the external temperature is near zero, as it is now, the inside temperature falls from the value set by the thermostat. The previous owner had a big workshop and some three phase equipment, I expect that he was keen on three phase for his workshop as well as his heating.

If your Daughter has kilns and might also have a heat pump, three phase might be the right choice. I would get expert advice from more than one person. Maybe the excess heat from the kilns can be stored, have a look at this http://www.earth.org.uk/milk-tanker-thermal-store.html from Damon's blog.

Most manufacturer's heat pumps are single phase up to about 12 Kw. A 12 Kw heat pump will take about 3.5 Kw from the supply. Beyond 12 Kw they are all 3 phase. As far as Nibe is concerned, the efficiency measured as COP stays about the same for single phase and three phase. Looking at the catalogue, the best COP (output @ 35 degrees) is 4.44 on a single phase machine of 8 Kw. The worst is 4.12 on a 5 Kw single phase and 17 Kw 3 phase.

Leak on manifold being repaired as I type. Hooray. Regards,..............Topher.

2 November 2010. Report 15.

The short cycling was 5 to 10 minutes running only. This was reducing the life of the compressor so I turned it off. I contacted Nibe UK who were brilliantly helpful.

Apparently I should have a return water temperature sensor about half way up the buffer cylinder. The 200 litre buffer cylinder acts an additional load, if I just had the relatively small amount of water in the underfloor pipes, the heat pump would rapidly reach the set temperature, causing short cycling.

As a temporary fix I strapped a temperature sensor on the return pipe going the heat pump. It works fine and now the heat pump runs for about 30 minutes before shutting down. I await Nibe UK to say if it can be left as a permanent solution, or if I need to fit a tube to the buffer cylinder to take the sensor.

When the pump has been running for some time, the water going into the under floor pipes is around 40 degrees. I think this is too high. My next task is to find out how to reduce this.

Hi Orangemannot,

You are right, I am being conservative with my old underfloor heating. I don't want to give it too much temperature cycling. The old plastic pipes are rated to 60 degrees, and I don't know how long they will last.

The other and probably more important reason is that the heat pump has its highest efficiency or COP at 35 degrees. At 60 degrees it falls to 2.71.

Your idea of having a bigger thermal mass with the thick screed sounds good, except that if the weather warms up, does the house feel too hot? And vice versa, when a sudden cold snap arrives, can the system respond?

The house came with three phase - I did not realise at the time the advantage I was getting

Regards,..............Topher.