@derek-m No, its a Grant Monowave Heat Pump Cylinder supplied by the installer. 

Posted by: @saf1973

@derek-m No, its a Grant Monowave Heat Pump Cylinder supplied by the installer. 

Hi,

The reason I asked the question is that if it had been a Daikin one, it would have been supplied with a 3-way diverter valve rather than two 2-way valves.

@derek-m well the HW Cylinder was another saga all by itself which nearly cancelled the install.  The airing cupboard upstairs is not full height so its needs a short (or wide) cylinder.   The first cylinder that turned up was too big so they had to go source elsewhere.  Ended up with a Grant Monowave Indirect Heat Pump 150lts.  This actually replaced the 125lts cylinder so I was getting a bit more water than before.  Its borderline on capacity requirements but we never ran out under the old system as I have flow restrictors on taps and showers.

@derek-m thanks for the tip - the installation manual for the Daikin Cylinders should be able to point the installers in the right direction, maybe its the Options Kit that they have bought.

Any thoughts on the North versus West scenario?

Posted by: @saf1973

@derek-m thanks for the tip - the installation manual for the Daikin Cylinders should be able to point the installers in the right direction, maybe its the Options Kit that they have bought.

 

Any thoughts on the North versus West scenario?

Hi,

As far as location is concerned, it is difficult to say without actually seeing the actual proposal. One thing that most manufacturers state is that the unit should not be located where it will be subject to strong winds at the exhaust side. The outdoor unit should also have as much space around it to ensure adequate airflow.

@saf1973

there are pros and cons of the outdoor unit being in sun or not.  If it's in the sun it may be a bit more efficient because the air may be warmer.  OTOH if it's in a sun trap it may make weather compensation a bit hit and miss as the outside temperature may not always vary in the same way as the heat loss from your house.  An ASHP in the shade will be a bit more predictable.  

As Derek says airflow is very more important.  

My ASHP is in a north facing, sheltered spot with plenty airflow and seems fine.

@derek-m does the backup heater perform the Disinfection Cycle or is that carried out by the immersion?   I don't have a cycle at the moment so I am doing it manually using the Solarboost override.   If it has nothing to do with the disinfection then its definitely optional, although the Daikin manual mentions it can be used if the HP stops working, so it is a "backup" rather than frost protection or boster device.

@saf1973 The disinfection cycle is done by the immersion, which in Daikin-speak is the Booster Heater. They refer to the Back Up Heater as the BUH.

Posted by: @saf1973

@derek-m does the backup heater perform the Disinfection Cycle or is that carried out by the immersion?   I don't have a cycle at the moment so I am doing it manually using the Solarboost override.   If it has nothing to do with the disinfection then its definitely optional, although the Daikin manual mentions it can be used if the HP stops working, so it is a "backup" rather than frost protection or boster device.

The backup heater can be used to heat the water coming out of the heat pump, so could be used for both DHW or CH, but of course is direct electrical heating so would be expensive to run. It could possibly be used for frost protection if the heat pump cannot produce any heat.

The immersion heater, or as is often referred to as the booster heater, can only heat the DHW, but again would be more expensive to run than the heat pump. For the disinfection cycle it would probably be most efficient to heat the water as high as possible using the heat pump, and then use the booster heater if it needs a higher temperature. Some of the manufacturers suggest heating the water in the hot water cylinder to at least 60C for a period of approximately 10 minutes, once every 7 days.

One step forward!

So I finally had another visit from the installer, this time a new plumber has turned up who seems to know his stuff and immediately spotted the lack of 3-way valve.  He has gone away to speak to Daikin regarding the DHW, backup heater and the interlock with the Evohome setup.   He made a good point that the buffer tank should not be in the DHW circuit so it looks like we have these two options.....

The difference being whether or not the backup heater will be used as a backup for the just the space heating (layout1), or backup for the whole system (layout 2).   I'm leaning towards having the backup just for space heating (layout 1) otherwise the backup heater will be doing too much.  Also, it would be pretty bad luck to lose the immersion and ASHP at the same time.

Also, when this is finally completed (and signed off) I may bypass the buffer if I can get it all tuned up nicely keeping enough Rads open......that is still a distant dream, first things first is to get it plumbed correctly.

Posted by: @saf1973

One step forward!

So I finally had another visit from the installer, this time a new plumber has turned up who seems to know his stuff and immediately spotted the lack of 3-way valve.  He has gone away to speak to Daikin regarding the DHW, backup heater and the interlock with the Evohome setup.   He made a good point that the buffer tank should not be in the DHW circuit so it looks like we have these two options.....

The difference being whether or not the backup heater will be used as a backup for the just the space heating (layout1), or backup for the whole system (layout 2).   I'm leaning towards having the backup just for space heating (layout 1) otherwise the backup heater will be doing too much.  Also, it would be pretty bad luck to lose the immersion and ASHP at the same time.

Also, when this is finally completed (and signed off) I may bypass the buffer if I can get it all tuned up nicely keeping enough Rads open......that is still a distant dream, first things first is to get it plumbed correctly.

Hi Saf,

I'm not certain if either of those two layouts would work very well.

I do believe there is already a water pump in the outdoor unit, so the internal and external pumps will both be on the same pipe, which is quite pointless, and may cause control problems. Also, when doing CH, the warm water entering the buffer tank is more likely to take the shortest route back to the heat pump through the buffer tank and not via the radiators. The external water pump would normally be installed in the outlet pipe from the buffer tank, and would therefore pump the water through the radiators. The flowrate of each of the two pumps would need to be balanced to minimise mixing within the buffer tank.

@derek-m

Yes, my mistake on the drawing, thanks for pointing it out.

 The new plumber is pretty much starting from fresh, he's done a survey, will talk to Daikin, measured up for new Rads where the rooms couldn't get up to temperature and will go away and do a report.  Hopefully things will start moving in the right direction now (no pun intended!).