New Heatpump install: fine-tuning/monitoring recommendations?

Hey all!

I just had underfloor heat, radiators, and heatpump installed and its been running for a few days now. Excited to finally have it after a long time planning this upgrade from electric resistance baseboard heaters! and now wish it was still cold out to really test it :sweat_smile:

I’ve setup a self hosted EmonCMS and linked it to, but I’m interested in any tips how to properly monitor it, and how to fine-tune the performance.

This is very uncommon for the area (air-to-air are much more common), so I’ve really had to lead the charge, studied up on hydronics, and convinced someone to help me install it.

The installer wouldn’t dare go for a buffer-less system (totally unheard of here), so I ended up with a massive buffer and second circulator. Maybe for the best given the climate (-23C design), and I’m seeing the condenser just ramp up to maximum output instead of running slow and steady like I was expecting. I hope that’s just a result of the warm weather. Its rated to supply 7kW at -23C, so its a bit (a lot) oversized at the moment…

The heatpump heats the buffer with a weather compensated setpoint. It has no interaction with indoor air thermostat. The thermostat just turns on/off the second circulator to supply the house from the buffer.

I’ve set up HeatpumpMonitor so that:

  • the Heat output is what’s added to the buffer,
  • but the FlowT/ReturnT are for the heat emitters,
  • FlowT/ReturnT are only logged when thermostat calls for heat and its circulator is running,
  • Target temp is buffer setpoint,
  • aux electrical inputs within the thermal envelop are added to the output (controls, pumps) since it nearly all gets converted to heat at the end of the day.

About performance, I find that the second circulator really eats away at the COP. Its a constant speed pump, so I’m testing higher FlowT with reduced pump speed and reduced runtime to see if that helps during warm weather.

I’m going to experiment with radiant cooling this summer. Anyone else doing that?

happy to join the club,

Hi Josh, welcome to the forum.

For other readers, here are the system details - a Gree Flexx 7 kW in Ottawa, Canada.

Your data collection is a little unusual, as systems usually report flow and return temps for the heat pump side of the buffer, but I can see the interest in knowing how hot the water is coming out the other side. This is probably fine from a metering perspective, but need to bear it in mind when comparing stats against other systems.

We don’t usually see heat output including electrical energy from the auxiliary components; I’m not sure how I feel about it. Your logic of “it nearly all gets converted into heat” is sound, just not common practice. It’s normal for standby and pump consumption to drag COP down. Be interesting to see what others think about that.

Looks like it took a little while to get the electrical metering sorted, so COP is a bit wild for the first day. You can crop the data by setting the ‘Start Date’ in the app to a timestamp, e.g. 1715313480 (5am May 10th).

I don’t know much about buffers, except that many of the top installers here aim to design system that don’t need them. In your case it’s there to provide hydronic separation between the primary and heating circuits, as well as to add volume for defrosts.

It’s quite common to see heat pumps eager to get up to temperature as quickly as possible, and it can be tricky to tame them. Your 7 kW unit is often delivering 11 kW of heat, which is considerably higher than the “3.66 kW @ -3°C” heat loss. If the controller has a “quiet mode” setting, this might help bring it down.

Can see here the heatpump putting heat into the buffer in short bursts, and the heating circuit then distributing that heat over a longer period. You won’t see steady running in mild weather, as the heating circuit can’t remove the heat as quickly as the heatpump can put it in, so it will cycle. Larger emitters or smaller heatpump would cycle less.

1 Like

Your data collection is a little unusual

That’s half my reason for posting - wanted some thoughts on that. I have the flow temps for heat pump side of the buffer as well if people think that’s the better metric? I guess it would be for comparisons.

I was using heat pump integrated metering for electricity input at first, but it was underreporting by quite a bit. When switching to proper metering and adding the aux inputs, I figured if I’m using so much power running the pumps, might as well include that heat in the output.

What is typical flow rates and circulator power?
On the heatpump side, I have 3020 L/h at 143W,
On the other side I estimate 795 L/h at 60W

do you use L/h or L/m ? Over here its all gpm.

a “quiet mode” setting

There is a dip switch on the heatpump board I used to put it into “energy saving” mode which is supposed to ramp up the compressor more slowly. I guess the elec input does increase over time… but there was another dip switch to derate the unit from 10.5kW to 7kW which doesn’t look like it worked based on the output…

Control seems to be binary ‘compressor call’ or not.

Hi Josh,

As I understand things, heat produced/delivered to the home is a product of the loss of temperature (dT) of the water and the volume of water.

COP/SCOP is the heat produced divided by the energy consumed by the heating system.

The energy consumed is everything to do with the heating system including circulation pumps and controls.

That is how most of the systems here are monitored.

How do your circulation pumps and controls add to the heat produced?

I don’t understand I have to admit.

All electrical appliances, fridges, televisions, light bulbs, chargers will emit waste heat into their surroundings, so the reasoning here is that the circulation pumps will do the same: adding heat directly into the home rather than via the heating circuit.

While technically true, this isn’t commonly how heat is measured and will skew the COP such that it isn’t comparable to other systems.

1 Like

Yup. I’m coming from 100% electric resistance heating. So when comparing to my previous setup, these are new sources of heat from the heatpump system - its just not being added into the water.

I can switch things up to make it more comparable to the other systems. I see that’s the point of HeatpumpMonitor after all!

On that same vein, to better compare with other systems here, should I exclude the secondary distribution pump energy? If all that matters is heatpump-to-water heating" ?

Most systems with secondary pumps do include their electrical consumption too. There’s parts of the form on HPM to document what is and is not included, so no need to exclude it from yours. The goal is to count all of the electricity required for the heating system to function, though there is variety amongst systems for various reasons.


This other recent topic on performance reporting may be of interest:

(one system criticised for not including pump energy, so will have a higher COP)