Hagg Leys Farm

Tag: nibe

Update on RHI

March 6, 2014 /

I went to three seminars today at Ecobuild 2014 on RHI.  A lot of the information that was presented in these session has been seen before.  However, there were some new snippets:

  • The launch date for domestic RHI has still to be confirmed, however, it is expected to be Spring 2014.  A number of the speakers referred to the date being finalised in the “next few weeks”;
  • The domestic RHI payments will be “deemed” (i.e. estimated) rather reliant on using installed meters.  The estimation will be based on the calculations completed as part of the MCS installation;
  • There are a couple of situations were meters will be required.  This is where the property is either a second home or there is an additional form of heating (e.g. gas boiler).  The metered payments will only be able to adjust the payment upto the deemed value, i.e. the metering will only be used to adjust the deemed payment downwards;
  • Applications for RHI will be administered by Ofgem.  Applications will be made on online and it is expected that applications should take 20-30 minutes to make.  In many cases, the decision of the online application will be instanteous;
  • The applications will require details from your MCS certification as well as your green deal assessment.  Hopefully, this will speed up the application process as details will be pulled in from these documents;
  • The government reserved the right to reduce the tariff by up to 20% should the RHI be over subscribed.

You will find more information on the Renewable Energy Association website.

Controlling the ground source heat

February 25, 2014 /

Or rather why we aren’t controlling the ground source heat pump!

A ground source heat pump extracts heat out of the ground to heat the house.  It works most effectively once the house has reached it’s target temperature.  At this point, the heat pump just trickles heat into the building to ensure that it stays at the set temperature.  In fact, it will often use additional energy from an immersion heater to get the house to it’s set temperature.

It can take a long time for the fabric of the house to warm up – in our case, it took a couple of weeks from a standing start.  However, I still suspect that the fabric of the house is warming up and drying out.  Let’s not forget that only a few months ago this building was open to the elements.

With this in mind, the NIBE engineer has told me to set the heat pump going and not to change it according to a schedule, or even when we go away on holidays.  If we were away for a few days, there would be little point in turning the heating off – it would take 3-4 days to cool down and then 3-4 days to warm up.  And we would probably use more energy in the process than we would if we just left it on all the time.  Let’s not forget with no one here, the windows and doors stay shut and the house is well insulated.  So heat loss would be a minimum.

It does, however, make sense to turn the hot water off.  It only takes around an hour to generate a full tank of hot water and that is from a standing start.  If the tank was full of hot water when it was turned off, it might only take 30 minutes to warm up depending on how long it had been turned off for.  I need to investigate how we can achieve this.  More updates later.

In terms of the other controls, we may control the secondary hot water pump (this pumps the hot water around the property to ensure that you get hot water out of the tap within a couple of seconds) and the valves for the towel rail circuits (there are two – one of the old part of the property and one for the new).  It will be very straightforward to control these using the Loxone kit.  We can set up schedules, over ride buttons as well as being able to access the controls remotely.

But other than that, there is little to control on the heat pump.  We have installed the latest software on the heat pump and this is automatically control the flow rates of the pumps to the underfloor heating and ground loops.  There are thermostats in all of the rooms that control the zone heating.  It would be straightforward to replace these with temperature sensors and actuators controlled by the Loxone kit, but it would have little benefit over what is already installed (re-badged Heat Miser units from NuHeat).

The ground source heat pump is still running!

February 24, 2014 /

After a rather “bumpy” start, I am glad to report that the ground source heat pump is still running!  It is providing all of the heating and hot water in the house since the 12th Feb.  This is much to our relief.

We still have some way to go in terms of getting all the room thermostats operational – the ones in the new extension have yet to be powered up.  We also have builders/decorators on site and it is difficult to keep the windows and doors closed all of the time.  So it is very likely that we will see some more improvements over the coming months.

Even so, the internal temperature seems to be doing well (even without the log burners going!).  However, it has yet to be fully tested in the real Yorkshire weather.  Today, it is a rather barmy 10C.

The ground source heat pump was repaired on the 12th Feb. You can see quite clearly the impact that this has had on the internal temperature of the house. The temperature gauge is in the downstairs bedroom were the temperature is set to 18C. It was also on the internal window cill where the sun (yes, it does happen occasionally in Yorkshire!) gets to it!

The ground source heat pump was repaired on the 12th Feb. You can see quite clearly the impact that this has had on the internal temperature of the house. The temperature gauge is in the downstairs bedroom were the temperature is set to 18C. It was also on the internal window cill where the sun (yes, it does happen occasionally in Yorkshire!) gets to it!

Update on the ground source heat pump

February 12, 2014 /

nibe logo

It looks as if the problem with the ground source heat pump has finally been fixed (although it would appear that there was no problem to be fixed).  It is going to take a few days for the house to get up to temperature, but at least it is a start.

The heat pump has been throwing LP (Low Pressure) alerts for the past couple of weeks.  The ground loops were flushed.  But there was no air in the system.  All of the strainers on the ground loops were checked.  Again, no problem.  The circulation pump for the ground loops was replaced.  But the same problem persisted.  The software on the heat pump was updated.  No difference.

The Nibe engineer spent 5 hours on site and finally struck on the idea that the temperature of internal underfloor heating was too low.  Apparently, there needs to be a significant temperature difference between the ground loops and the underfloor heating otherwise the low temperature in the underfloor heating will reduce the temperature (and thus the pressure) on the ground loops.

The answer appears to be to use the internal immersion heater to raise the temperature of the underfloor heating.  Then the ground source heat pump could be engaged and, voila, it all works as it should.

We restarted the heat pump about 6 hours ago (around 4pm this afternoon) after engaging the immersion heater for a while.  The good news is that it is still running (and generating heat).  Fingers crossed.

Here's the graph for the internal temperature from our weather station. You can see where the heat pump was turned on around 4pm. Hopefully, the graph overnight will look just as good. Fingers crossed.

Here’s the graph for the internal temperature from our weather station. You can see where the heat pump was turned on around 4pm. Hopefully, the graph overnight will look just as good. Fingers crossed.

Ground source heat pump

January 19, 2014 /

We finally got the ground source heat pump up and running on Thursday.  The commissioning took most of the day with the majority of the time taken up getting the antifreeze into the ground loops (the pipes that run underneath the field).  There is around 125 gallons of antifreeze (glycol) in the 1800m of ground loops.

The ground source heat pump was powered up around 4pm on Thursday.  It took around an hour to heat up the hot water tank (500l).  Once the hot water tank was up to temperature, we turned on the underfloor heating.  It will probably take until next week before the building is up to full temperature (21c), but the building felt warmer the next morning.

With 125 gallons of anti-freeze installed in the ground loops, we have around 30-35 gallons left over. Not sure what to do with this. Maybe ebay?

With 125 gallons of anti-freeze installed in the ground loops, we have around 30-35 gallons left over. Not sure what to do with this. Maybe ebay?

Apparently this anti freeze will detriorate if left in the sun for a significant period of time. If you are going to store it outdoors, do make sure that it is under cover.

Apparently this anti freeze will detriorate if left in the sun for a significant period of time. If you are going to store it outdoors, do make sure that it is under cover.

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