@derek-m thanks for the update, I've had it switched off for a few weeks for the purpose of my testing. There is actually no control on this install yet other than LWT. I've lowered the temp to 40C as I am also challenging the installers lack of radiator upgrades (for another thread!) I have has to run the DHW manually by opening up that 2-port and raising the temperature, but sometimes i forget or cant get back to manually close that valve and lower the temp so my bills have been high.
Radiators all are sized for peak load AND a rapid heat up time. If the rapid heat up time is designed out with weather compensation there is no need to replace radiators..
@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.
@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.
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.
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.
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!).
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!).
An alternative, if the internal water pump in the outdoor unit is man enough, would be to disconnect both return water pipes from the buffer tank and connect them together. Fit plugs to the buffer tank connections and remove the external water pump. The buffer tank would then just act as a capacity vessel, and there would be no chance of the flow and return water mixing.
March update! I've had another plumber around today, all on his own, ripped out the mess that was there and replumbed in a day as well as moved the outside unit for more flow, levelling it up and lag it all. Its just a shame its taken Solartherm 15 months to get to this point.
So here's the schematic that has been implemented, a huge improvement in temperature already, its 6degrees outside now and the house is too warm with a flow at 40C (apart from the undersized rads rooms).
The job is not finished yet, the controller is either duff or has been locked somehow as it only shows the date/time menu and allows LWT temperature adjustment (up/down), nothing else. Its ERKUCBL2 - does anyone know how to reset it to factory to see if the menus appear?
Also, 3 rads still to change, add glycol and install the replacement controller in the hallway rather than in the hot cupboard. Plus take all the EVOhome TRVs off, although i may leave 2 rooms with them on where i want lower temperatures.
and of course the DHW still isnt working as there is no control or stat to operate it.
Less than two weeks before RHI registration closes so its a tight one........ i have an MCS/NICEIC complaint logged for the record in case we end up in court should this not be registered with RHI in time.
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