Bramco

You obviously live alone... Where thermostats have a display, isn't that what the display is?

You're making the assumption that someone in the house (you know who I'm talking about) can guess the temperature without looking at the app - ain't gonna happen..... 😄

Could do but... In our setup, we only need to run the ASHP at night to batch charge the insulated slab. When it is cold, all the rooms need the full 6 hours or so. When it is less cold, the thermostats will cut off the flow when the set temperature is reached. So for the downstairs bedroom it cuts the flow off earlier than the other two living area zones - the set point is lower. I do set the thermostats in 1 hour intervals starting a couple of degrees higher than needed and decreasing the setpoint every hour. This makes sure that the thermostats don't dick around with the ASHP by tuning it on and off at short intervals. Again this seems to work fine.

Thanks for the suggestions guys - I'd put solving this on the back burner as we had a workable if slightly more expensive solution - think I probably need to give this a bit higher priority on the to-do list.... The UFH buffer tank is a smaller Newark tank (140l) - earlier when I contacted them, they said they put either one or two coils to get the 3m2 surface arear depending on the size of the cylinder. So I guess they always put two in on one that is 140l. Our 300l DHW tank has only one.

@Wil thanks and I know how to do the change manually - there's a few owners on another thread trying to work out how to do it automatically. I wonder if we maybe haven't the same unit - mine is wired using pairs on a cat5 cable, not through an rj45 connector. Do you have the pinout for your connector.

Thanks

I know I do.... 🙂 Long discussion here -> https://community.openenergymonitor.org/t/water-hammer-noises-and-heat-pump/26263 And you've been short changed - mine has a couple of those. 😄 and they haven't worked on the air trapped in the corrugations in the DHW tank.

It's been stated many times...... 😄 Sadly we have a DHW tank with an ASHP coil (3m2) BUT it's corrugated which leads to a lot of noise from air trapped in the corrugations. Manufacturer says - your problem mate. The fix is to replumb with a deareator etc to try to get rid of the air. So given we lose a bit on using the diverter rather than the ASHP, we have some way to go before it cancels out the cost of the replumbing - I'd also add a heat meter and the kit to be able to monitor the CoP, so it's not a cheap solution fix - and it may not work!

Could do that and tbh, in the summer the tank is hot to overflowing with all the solar divert. I'd just have to remember to go back to heating only before the winter. Although at ambient it wouldn't come on anyway...

@Wil @MikeSharp01 @alfaTom Looks like you all have been through the CE MCS scheme and self installed. I'm assuming that when the unit arrived, there was some detail on what connections to make between the indoor Carel user interface and the ASHP itself. I've worked out which additional connections can be used to switch between Heating and Cooling but can't work out how to turn off Hot Water. So wondered if the connection instructions you received had this info?

DI-6 works the same way as DI-4. So connecting to GND (8) sets the unit in 'Hot Water + Cooling/Heating' depending on which one is connected. Given we don't use the Hot Water modes, only Cooling or Heating, I'm going to have to find out how to switch off Hot Water....

Good question. I've redone the experiment swapping from heating to cooling and when I look in the app to set things back to heating, it shows the unit as being in cooling + DHW. So it looks as though connecting DI-4 to ground hasn't set the unit to just cooling, it's set it to cooling +DHW. Which means, I'll have to find out how to turn off DHW as we only use the unit for heating and cooling..... I'll attach another wire to the DI-6 for setting things back to heating to see what happens. Can't see anything on the schematics for DHW - although the schematics are very blurry, so it's hard to tell.

You'll have to connect DI-6 to common to put the unit back in heating mode. DI-4 and DI-6 are latches, so making the contact and breaking it doesn't return the unit to the previous mode. I'm going to build something in parallel to the thermostats which when activated will run cooling at night on the cheap rate. I'll also have a boost button for, say, 3 hours for when we need additional cooling during the day. Will also make it accessible through Google Home, so if we're away for a long time, I can turn it on remotely.

@HughF Interesting - it works as a latch. (Probably should have expected this thinking about it). So when you connect DI-4 to GND, the unit switches from heating to cooling. But when you disconnect it, it stays on cooling, so you'd have to connect DI-3 to GND to get it to switch back to heating, or do that on the controller or app. With a suitable relay, you could switch to cooling and then drop back to heating but you'd need 3 wires. Simon

@HughF thanks - there's a spare pair on the cat 5 into the house, so I'll rig that up with a switch in the house to see what it does. Simon