the most energy efficient way to operate your under floor heating is at low temperature with a continuous flow

I agree that without evidence suggesting otherwise, this is probably the way to go.  But this could be a moot point ...

... and likely depends on other factors  If you are on economy 7 and have good thermal mass in your UFH you should get  7 hours electricity at 16p and 17 hours at 47p.  The CoP needs to be 3 times better during the 17 hours (on average) to justify running it through the 17 hours as well. 

Things to consider though

1. the heat pump is working much harder at night and running a number of defrost cycles (right now - that should stop at some point in spring)
2. there is the cost of wear and tear (which is probably higher at night - due to low outside temp and the higher flow temperatures)
3. a yoyo of temperatures (maybe not good for the floor - expand/contract a lot)
4. upstairs UFH does not have the same thermal mass as downstairs (can be fixed by zoning)
5. option of using solar in the day, if you have it, or battery may offset the costs allowing you to be on a cheaper all day tarrif

I am still trying to work out the best option, since there are some "costs" that are not that easy to quantify.

Hi @sunandair , so if I’ve understood correctly, you believe the pump running 24/7 is ok/normal?

No, that’s a  slightly different slant on what I said. My point was that when you’ve resolved any problems you may have with your system you may find the most energy efficient way to operate your under floor heating is at low temperature with a continuous flow. 

One other quick question, people keep referencing “pumps”.  I only have one circulation pump - am I missing something…maybe you’re systems are all bigger?

Thanks.

You obviously have failed your observancy test, since you failed to notice that I had not attached the referenced manual.

One other quick question, people keep referencing “pumps”.  I only have one circulation pump - am I missing something…maybe you’re systems are all bigger?

Thanks.

The main water pump should be wired to OUT1 on terminal block TBO.1 connections 1 & 2 as shown on page B-46 of the attached manual. I would suggest that you also check the water pump economy setting as shown on page B-70 and the freeze stat setting as mentioned on page B-72.

One other quick question, people keep referencing “pumps”.  I only have one circulation pump - am I missing something…maybe you’re systems are all bigger?

Thanks.

You are one of the lucky ones to only have the one water pump, which would indicate that you don't have the unnecessary complexity that has been built into other systems. Having just one water pump will not only slightly reduce electricity consumption, it will also mean that you don't have a buffer tank, low loss header or plate heat exchanger installed, any of which can seriously effect overall efficiency.

Obviously, your water pump should operate whenever your heat pump is supplying the central heating or DHW, but may also run - on for a period of time after the heat pump has stopped. There are also settings to periodically run the water pump for a short period of time, even when the heat pump is stopped, to ensure that the water temperature sensors are measuring the average temperature. I will have to look at the manual, but I believe that the water pump can also be set to run continuously.

One other quick question, people keep referencing “pumps”.  I only have one circulation pump - am I missing something…maybe you’re systems are all bigger?

Thanks.

Me too.  Waaay past 😆 

it just feels odd that the circulation pump runs 24/7, although I guess the electrical consumption isn’t going to be that high?

on a separate note, please can you help me with setting up the energy consumption and produced data.  It show blank at the moment per the photos I posted and I can’t work out how to get that working?

thanks in advance.  Adam.

The wiring diagram I studied recently, shows the main and any auxiliary water pumps wired to the main Mitsubishi control panel. Is that the case with your system?

I’m not sure if we’ve just not installed correctly.   Maybe the circulation pump needs to have the same ‘run’ signal as provided to the external ashp?  

This would make sense to me as I would think something needs to tell the circulation pump to run (as the ashp needs to be told to run).  If it’s not a wiring connection in the Mitsubishi control panel then maybe there is another setting on the keypad?

I’m past my knowledge level though!

Someone will need to tell you how to set up consumption and production data I'm afraid.  Mine was set up by the installer.