Appreciate assistance with monitoring HW choice & placement

Good afternoon,

I have been on the fence for getting a heat pump monitoring system installed for a while - to get the full pre-configured bundle is close to £1k.

I have a Grant Aerona 3 17kW heat pump, while this is working in as much as the house is warmer than when using the old gas boiler I think there are more efficiencies to be had. I have already enabled weather compensation which reduced consumption without affecting comfort, but I have no way to monitor further changes effectively. I know I need to improve the external pipe insulation, the fitters only used the normal Armaflex, not the outdoor rated stuff. The system is filled with water only, no glycol or inhibitor.

I have a heating company coming next month to replace radiators that I know are undersized and while they are here I would like them to fit other kit in the plant room while the system is drained down:

  • heat meter
  • air separator
  • flush & fill valve (with flow meter)
  • mesh strainer

Before I commit to a purchase of items, I would appreciate some feedback on the intended placement and use.

The heat meter I am looking at is the Kamstrup 403 q3.5. This will be installed on the return pipe between HP Mag Filter and buffer tank between 2x ball isolation valves. The instructions don’t state clear space either side of the heat meter so I am assuming 300mm either side (taking the 5x pipe diameter value from the flush & fill valve instructions).

I want to also install a mesh filter to complement the Mag Filter - is this appropriate or overkill given I’ve got the Mag Filter? Or will it negatively affect flow when in normal use (filter cleaned regularly). If it is to be installed should it go before or after the Heat Meter on the return pipe between the isolation valves? I am considering the 28mm Altecnic 400 mesh filter.

The air separator will be installed on the flow from the heat pump before the buffer. I am considering close to where the Mag Filter is located in the corner.

For the Flush and fill valve:

  • instructions state 300mm straight pipe upstream of the valve (I assume here direction of water flow)
  • should it be on the heating flow from buffer or return to buffer?
  • if on heating flow I’ll have to get the pump lowered to fit the valve on the outlet side of pump
  • if on heating return it’ll go beneath the Mag Filter and tee to the expansion vessel
  • This is being fitted to confirm matched (or close to) flow rates for the HP side and heating side of the buffer.

OEM Kit considerations:
I already have an emonPi in the garage (currently monitoring solar & grid), a emonTX v4 alongside (monitoring EV charge points & battery) and another emonTX v4 in the plant room (monitoring ASHP and Mixergy cylinder via CT clamps).

To avoid spending extra on the full monitoring bundle or buying an additional emonBase I am considering:

Moving EmonPi from garage to plant room:

  • connect ModBus USB for electric meters (2x or 3x SD120 ModBus meters)
  • connect mbus usb for heat meter
  • 2 spare CT Clamps to then be used to monitor individual live cables so I can separate out usage figures for controls from “in use” consumption

Move emonTX v4 (Wi-Fi) from Plant Room to Garage:

  • CT clamp to solar
  • CT clamp to Grid
  • CT clamp to PowerWalls (2x live passing through single CT)
    Existing emonTX v4 - need to buy Wi-Fi module for it):
  • CT clamp to Zappi 1
  • CT clamp to Zappi 2
  • CT clamp to Ohme
  • CT clamp to Wallbox

What would be involved in changing sensors around in my emonPi config / local emonCMS so I don’t lose historic data? Backups will be taken before hand!


Have you installed this yourself?

Is it all radiators, size of main pipeworks to those radiators please ?

Why do you have a buffer ?

1/Every heat pump should have (tea strainer) type filter on them.

2/ be careful with fil, flush and flow setter valves, then can be very restrictive.
We don’t use them on our installs, but we can see the flow rates on the controllers.
I know the Grant doesn’t have this.

3/ why do you need a de aerator

We just run water in most of our systems, maybe a little biocide.

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Not fitted myself, but have been going back over the installation as originally things like the internal insulation was installed over pipe clips leaving huge gaps, etc. Admittedly gaffer tape probably isn’t considered the best way to join the insulation but I’ve got a lot of it and it does the job better than cable ties. I’ve sorted the weather compensation too as it was originally installed at fixed flow, that made a lot of difference to consumption.

Yes, all radiator house. A heat loss report was done prior to install with recommendations to replace most radiators. I wasn’t ready for that last year so just went for the heat pump install.

Now 9 new radiators are going in with 2 swaps. K2s for K3s and K1s for K2s. Only the hallway and landing is still technically undersized but I will live with that.

28mm primaries with tees off in 15mm dropping to 10mm or straight to 10mm to every radiator (depending on whether it’s the original part of the house or extension).

From the heat pump is 28mm too, with the supply from the buffer also piped in 28mm and joined to the original system under the landing floor. Probably 10m maximum new piping to get to the original.

I know Grant now specify a LLH for their installs but at the time a buffer was an option. Knowing my radiators were undersized I wanted the buffer to minimise cycling of the heat pump and to give the hp something to draw off for defrost rather than cooling the radiators.

Mine doesn’t, only the Mag Filter on the return (supplied with the heat pump) and the same model (that I already had from my existing system) fitted to the return from the radiators.

Ok, understood. It’s the Intatec INFBV2850 rated at 10 - 50l/min that I’m looking at. Purely to get the flow rate after the buffer to compare with flow reported by the heat meter to try and keep both sides balanced as I’ve read this is preferred. The flush and fill but is a nice to have.

If not the Intatec, is there a flow meter that comes recommended?

The information available from the Grant is quite limited, no where near what you can get from a Vaillant. But they were rarer than rocking horse … last year so here I am with the Grant.

I’m not sure I “need” one, but with only using tap water to fill the system with nothing else I thought it was a preventative measure to reduce risk of corrosion further. Maybe I’ve fallen for the sales spiel?!

I’ve seen a few people on Twitter who say this, hence why I thought I’d give it a try.

Thank you.

Change the buffer to a 2 pipe volumiser,.ditch the post buffer pump, the Grant has a fixed 3 speed pump,(change setting on dip switches if needed)

Unfortunately Grant are clueless, I was part of a team that were invited to engage/meeting with them about hydronic design.

The Grant is ok, it’s actually a Chofu unit and it has alot of settings you can engage with.

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Forgive my ignorance but do I achieve the same outcome by removing the 2x return connections to the current buffer (capping them off on the tank) and joining the pipes together?

Thank you

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I would pipe it like the screenshot I’ve sent you, but on the return from the heating going back to the Grant.

Thank you for your help, I do appreciate it.

So like this…

Take return from bottom right port (& cap it) to top right port
Disconnect & cap top left port
Connect heating flow directly to heat pump flow
Remove 2nd pump

That’s it, but put heating return to top left, bottom right return leave as is. So your green line move to the left.

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For sake of completeness…