Intergrating stove ,solar thermal and ground source heat pump.

[Worcester]

Also shame that for the DHW consumption they didn't use the official standard - they exist specifically for this reason.

Tapping Cycle No.2 from EN 13203-2. Tapping cycles are set daily profiles of hot water draws, including the start times and energy per draw, developed by industry to enable different appliances to be tested with exactly the same hot water load.

Tapping Cycle No.2 means 5.845 kWh of energy is contained within the water drawn per day.

The actual volume of water drawn depends on the inlet and outlet temperatures – if the water is heated from 10 to 50°C, this equates to 124 litres per day. This unit under test is set to 55°C as per the manufacturer instructions; actual tank temperature varies between 49.4 and 57°C as it cycles on and off on the controls. The cold water feed average for February is 10.7°C.

Results for February (1st – 20th) show the daily hot water volume to be an average of 114.6 litres, with a minimum of 111 and maximum of 118. For comparison, a 2008 study by EST [1] found the mean household consumption to be 122 litres/day, using data from about 120 houses. The Government’s Standard Assessment Procedure, SAP 2009 [2] uses 36+(25*N) litres per day, so for 3 people this is 111 litres and for 4 people 136 litres. The tapping cycle is therefore very representative.

If a lower set point were used, e.g. 50°C, then more hot water volume would be drawn to make up the 5.845kWh daily demand.

For more details, please look to BS EN 13203-2:2006

That's the problem with govt appointed consultants - making up their own tests !

 

[Nostrum]

Thermia diplomat inverter, 3 phase only for the minute but single phase is coming.

You'll see them enter the market in the next 12-18 months from most manufacturers. I've been to Sweden to see thier factory and spoken to some of the head honchos about inverter technology.

It seems that the only reason they're investing into it is because the likes of Mitsibishi, Samsung etc have forced the market down this route with their air con technology.

Buffer volumes up to about 200 litres tend not to allow for very efficient stratification, so mixing will occur on a 4 port set up. We've still been advised to use them in this way where hydraulic separation is required, but return in series is favoured.

Another configuration is a 3 port whereby the flow passes through the buffer in series, but with the addition of a return from buffer if flow rates through emitter circuits drop off.

 

[JonG1]

Heliotherm and Mastertherm (i think) make fully modulating ground source units. The Heliotherm is very expensive and in tests performs no better in terms of SCOP than high end GSHP's like IDM etc.

They and IDM are more than happy for you to go direct to screed provided volume and flow rate are available. The reason we started doing 4 pipe buffers at 30l per kw was due to the mixing that occurred in the smaller buffers.

Over the long haul the impact is probably negligible and so many other factors to take into consideration like location of buffer, type of property, interlock, cyclical rate of downstream controls etc. There is no perfect solution.