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Water pump operation choices on my Harnitek heat pump

 
Thermostats, Volumisers, Buffer Tanks, TRVs, Pumps, Piping, Valves, Radiators & Controls
Last Post by ivanhoew 1 year ago
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 ivanhoew
(@ivanhoew)
Eminent Member Member
Joined: 1 year ago
Posts: 28
Topic starter 03/02/2025 3:06 pm  

Hi Chaps

I am looking at the water pump operation choices on my Harnitek  heat pump .

 

i have three choices in the software options ,these are..

1) interval working mode

2) on constantly

3) off with compressor .

choice 1 is programmable, so it switchs off with the compressor, but then switches on for a set amount of time , and then off again for a set amunt of time , at the factory setting, its off for 6 mins then on for 1 min  etc .repeating .

as far i  i can tell with my data logging , this does not work at all , and it simply goes on and of with the compressor .

so i wonder , how do other ASHP's control their water pumps ?


This topic was modified 1 year ago by Mars

   
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Transparent
 Transparent
(@transparent)
Famed Member Moderator
Joined: 4 years ago
Posts: 3093
03/02/2025 4:01 pm  

O-er @ivanhoew

You are going to get a mixture of replies to that.
Let me start by suggesting how your heat-pump should've been commissioned....

 

1: An ASHP should operate continuously, rather than cycle on/off in response to external control (from a thermostat).
That being so, the compressor won't ever be off.

 

2: Most water circulation pumps have their speed adjusted according to the required flow-rate.

There are pumps which incorporate their own speed modulation...
... but the pump is generally controlled by a (digital) signal supplied from the heat-pump.

So your question implies that your system has been fitted with a circulation pump without modulation 😥 

 

Can I suggest you give us the model numbers for the ASHP and the circulation pump.
If you can photograph the latter, that would be better still.

Building Regulations, Part-L, section-9 requires you to have been provided with site specific information on what has actually been installed in your home.
Do have the system diagram which you could post here?

Part L 9

This post was modified 1 year ago by Transparent

Save energy... recycle electrons!


   
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 ivanhoew
(@ivanhoew)
Eminent Member Member
Joined: 1 year ago
Posts: 28
Topic starter 03/02/2025 8:56 pm  

its a harnitek 12V1TBA-250L ashp , PUMPis intgral to the harnitek indoor 250 litre tank cabinet , controlled by the harnitek ecu .

 

pump model is WILO PARA 25-130 /987/1PWM1.

i think this is an ac pwm unit . i can datalog a varying pwm signal , but , when it does this it's also showing as pump status status 0, as opposed to pump 1 which i asumed means its on .

the system runs weather comp ,set v low ,27-31c  and cycles  between every 20 minutes and greater depending on the FT and ambient .

 

Re:

"1: An ASHP should operate continuously, rather than cycle on/off in response to external control (from a thermostat).
That being so, the compressor won't ever be off."

 

 

I would love to see an example of a heat pump installation that operates  continuously ,with the compressor never being off ,with no cycling  , in all weathers and times of year   ?

from what i have read on here , especially clockworks thread on cycling , it seeems a lot of heat pumps switch on and off ,gaps  anywhere from 20 m to an hour . .

what i want to know is what happens to thier circulation pumps when that cycling is happening .

i can log and show graphs if it helps to understand what i mean . 🙂

 

regards

robert

 



   
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Transparent
 Transparent
(@transparent)
Famed Member Moderator
Joined: 4 years ago
Posts: 3093
04/02/2025 10:37 am  

So you have this model with an integrated 250-litre DHW cylinder.

image

 

Posted by: @ivanhoew
↑

pump model is WILO PARA 25-130 /987/1PWM1.

i think this is an ac pwm unit . i can datalog a varying pwm signal , but , when it does this it's also showing as pump status status 0, as opposed to pump 1 which i asumed means its on .

The Harnitek data sheet suggests that there are (at least) two pumps

  1. inside the internal unit, supplying water to the 4-port buffer tank
  2. after the buffer, in the flow pipe to your radiators, alongside a motorised mixer valve

 

That requires some detailed expertise/knowledge to commission.

The two circulation pumps could be fighting each other, with the buffer-tank standing between them.

At this stage I don't know which pump you're referring to, let alone how the Harnitek firmware is adjusting the pump speeds in response to the flow/temperature sensors.
Their literature suggests this is a 'black box' which can be quickly installed and that it sorts itself out 🤔 

How are you "datalogging a varying pwm signal"?

How does that correspond to what the Harnitek App/Display states?

 

Posted by: @ivanhoew
↑

it seeems a lot of heat pumps switch on and off ,gaps  anywhere from 20 m to an hour . .

what i want to know is what happens to thier circulation pumps when that cycling is happening .

I think that question is going to tax the combined efforts of @jamespa @cathoderay and @majordennisbloodnok
because what happens with other ASHPs may not reflect what Harnitek's algorithms do.

What buffer-tank do you have and what sensors are connected to it for flow and temperature readings?

 

Do you have:

  • the commissioning checklist sheet?
  • the site-specific system schematic for your particular installation?
  • the energy survey report with its system design parameters?

 


Save energy... recycle electrons!


   
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 ivanhoew
(@ivanhoew)
Eminent Member Member
Joined: 1 year ago
Posts: 28
Topic starter 04/02/2025 11:57 am  

ThanksTP ,  no, no buffer tank, one pump .

 

i log the pwm on my inbuilt harnitek logging SW .

 

RE: 

 

"Do you have:

  • the commissioning checklist sheet?
  • the site-specific system schematic for your particular installation?
  • the energy survey report with its system design parameters?"

 

 

 

nope none of the above ,  just the user manual , and the wi fi dongle to connect the pump ecu to my laptop .

 

dont get me started on eco4 install support !!

 

i recognise other makes may have different methods , thats what i wanted to know , what those methods are .

 

with my system i can change all the parameters , but am curious to know what other makes deem the best more efficient way to run the water pump , on all the time , on only with the compressor , or on and off at times intervals independant of whether the ashp is running .

heres an example of compressor and water pump speed changes as logged ...

Heat Pump(7)

 if yuo look at the legend above you can see what colour means what , and that when the ashp tuns off , so does the water pump , at least its status goes to zero , which i assume meansx its off ...even when its pwm is showing an adjustment ! very odd .

 

regards

robert

 

 

 

 

 



   
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