@jamespa Thanks. Did you mean to give examples of the thermocouples? 

So at the moment, I will leave things as they are and wait until the heating starts in the Autumn.

Posted by: @richard24738

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@jamespa Thanks. Did you mean to give examples of the thermocouples? 

So at the moment, I will leave things as they are and wait until the heating starts in the Autumn.

Yes, and I did (I hope).  The word here above is a hyperlink to an Amazon offering.

@jamespa Thanks.

Hi Richard,

Re: Temperature Measurements:

Water Meters:

Water Meters are  the best method to measure the water Temperature within a pipe.

However, Water meters need accurate sensors fitted inside the water flow . 

Fitting these sensors can be difficult and expensive.

Thermocouples:

Thermocouples are cheap but can only measure the Temperature of the Water pipe itself, not the Temperature of the water within.

Thermocouples are prone to drift with many ( most)  meters fitted with "Offsets Controls " to offset drifting.

Thermocouples can be glued to the pipe with thermal conducting paste, messy and inflexible.

Thermocouples can be attached with commercially available bright Yellow clamps, flexible but costly .

Thermocouple Clamps are readily available on Ebay.

DS18B20 Semiconductors:

These Semiconductors offer a far more accurate , and stable Temperature Measurement when attached to the outside of the water pipe.

The DS18B20 are cheap , however, some fakes have appeared on the market of late.

Several DS18B20 's can be easily attached to one "Arduino" Microprocessor.

Where to fit Temperature Sensors:

Try to fit your sensors at the start of the Radiator water circuit not at the output of the Heat Pump itself.

Heat Pump makers routinely boast of the COP of their devices when measured at the heat Pump itself.

Your Installer will have fitted numerous Lossy buffers, Pipes et al between the Heat Pump and your house, so, try to measure the performance of the total system .........not the Heat Pump itself.

ian

Posted by: @iantelescope

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Where to fit Temperature Sensors:

Try to fit your sensors at the start of the Radiator water circuit not at the output of the Heat Pump itself.

I would say fit them where you need the measurements, which depends on what you are trying to work out!  If you are trying to work out the change in flow temperature across the buffer, then fit them either side of the buffer as I suggested upthread.

@iantelescope is right that thermocouples can drift, mostly (I believe) because the temperature of the reference drifts.  However with one of the dual sensors I gave the link to (a) the reference is likely to be the same for both sensors and (b) you can always swap the two round, thus checking any measurement.  You are only looking for a difference in this case, not an absolute, and you aren't looking to monitor it continuously.

Posted by: @iantelescope

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Heat Pump makers routinely boast of the COP of their devices when measured at the heat Pump itself.

Thats not really boosting COP of their devices, and certainly not in any deceptive way.  They are quoting the performance of the device they are supplying.  They aren't responsible for the rest of the system

Posted by: @iantelescope

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Your Installer will have fitted numerous Lossy buffers, Pipes et al between the Heat Pump and your house, so, try to measure the performance of the total system .........not the Heat Pump itself.

Hopefully only one buffer/LLH as reported, and hopefully its within the thermal envelope.  That's probably one too many than is actually necessary, but not 'numerous'.  Pipes aren't really lossy if they within the thermal envelope, because the 'lost' heat is useful.  Outside the thermal envelope they should be well insulated.  

@richard24738 

Hi Richard.

"Short Cycling, causes and cures"

My Heat Pump has been "Short Cycling " since installation in July 2022 resulting in ink like pipe water.

The "Short cycling" has , at least, three different causes.

I have, finally, discovered the last of the causes of "Short Cycling"

!:Short Cycling Thermostat:

My Heat Pump was, eventually,  installed by my installer with an "Honeywell Home  " Thermostat.

The "Honeywell Home" Thermostat has a "Cycling Rate Control " which was set to 6 cycles per hour, or, a cycle period of exactly 10 minutes.

I have set the Cycling Rate  Control to 3 per hour greatly reducing , but not eliminating,  short Cycling.

2: Short Cycling And Water Volume:

My Heat Pump , supplying Two Water circuits had ,already, an  inadequate pipe Water Volume.

The Time taken to heat up and release heat from these water volumes resulted in further "Short Cycling".

Samsung , my Heat Pump manufacturer recommended the installation of a Buffer tank.

The buffer tank does , however, increase the system energy losses.

3: Short Cycling and System Cycle control:

My Samsung Heat Pump has a control used to extend cycle time .

The Control switches the Two water Pumps after a  7/8  minute delay.

My Heat Pump, costing to date circa 14K , cannot be economically repaired with the MCS/NIC saying that , " nothing can be now be done".

ian

Posted by: @iantelescope

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My Heat Pump, costing to date circa 14K , cannot be economically repaired with the MCS/NIC saying that , " nothing can be now be done".

 

ian

@iantelescope  Both @derek-m and I have made (very similar) suggestions as to how your installation can be improved, explained why implementing them would be expected to make a difference, and subjected those suggestions and the explanations to peer review through this forum.  However you have declined to follow the advice offered.  It is very unfortunate that your installation is, it seems, sub-optimal, but that doesn't mean that it cant be significantly improved.  I am (and doubtless @derek-m is) very sympathetic however it remains the fact that if you change nothing, then nothing will change.  MCS/NIC saying 'nothing can now be done' is doubtless a contractual not a technical response.

Posted by: @jamespa

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Posted by: @iantelescope

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My Heat Pump, costing to date circa 14K , cannot be economically repaired with the MCS/NIC saying that , " nothing can be now be done".

 

ian

 

@iantelescope  Both @derek-m and I have made (very similar) suggestions as to how your installation can be improved, explained why implementing them would be expected to make a difference, and subjected those suggestions and the explanations to peer review through this forum.  However you have declined to follow the advice offered.  It is very unfortunate that your installation is, it seems, sub-optimal, but that doesn't mean that it cant be significantly improved.  I am (and doubtless @derek-m is) very sympathetic however it remains the fact that if you change nothing, then nothing will change.  MCS/NIC saying 'nothing can now be done' is doubtless a contractual not a technical response.

As the saying goes "You can take a horse to water, but you cannot force it to drink".

Not sure why my original thread has gone down this route.

Anyway, thanks to everyone for your comments. 

Posted by: @richard24738

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Not sure why my original thread has gone down this route.

Anyway, thanks to everyone for your comments. 

My comment was not aimed at you or your situation. I was merely reminding James that he, I and others on the forum spent a great deal of time and effort trying to identify the problems with Ian's system and suggest possible solutions.

Most, if not all, of our suggestions were ignored by Ian, who even now continues to moan about his poorly performing system.

@iantelescope Sounds like you have a very similar system to mine. I too have a Honeywell Home thermostat connected to a Samsung 12Kw HT Quiet heat pump plus a backup oil boiler in a bivalent arrangement.

The thermostat controls the HP and when in backup boiler mode, controls the oil boiler. The thermostat is configured to have 3 cycles (20min each cycle) per hour due to oil boilers not liking frequent cycling, 6 cycles is for Gas.

The issue I was having was the thermostat would learn to demand heat for 80% - 90% of the cycle time but my heat pump was set to water pump option 4 (field option #2092) causing the heat pump to start up for 3mins then shutdown for 7 mins during the room thermostat demand time, looking like short cycling but I think it is suppose to be an energy saving thing. However I felt that this was not working very well with the external Honeywell thermostat although probably fine with the built in thermostat.

I have also noticed my HP is required to run for a least 8mins+ due to various eco stages to get full heat output according to the water law (weather comp) so 3 mins was killing the heat output.

I have now changed the field option #2092 to option 3 so now when the Honeywell thermostat demands heat, the circulating pumps run continuously for that period and the compressor runs until it reaches the water law (weather comp) temperature and then either slows down or stops until the circulating water cools enough for it to kick back in.

This has now enabled me to reduce my weather comp curve to 35C @ 10C OAT to 45C @ -2C OAT, the house still gets to 21C and the Honeywell thermostat is practically demanding heat for 90% of each cycle time. The heat pump seems to be a lot happier and now draws 1.4Kw instead of 1.9Kw in electricity. Since adjusting at the end of March 2024 my COP now = 4.4 up from 4.15

Hope this is of some use 🙂

Posted by: @technogeek

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The thermostat controls the HP and when in backup boiler mode, controls the oil boiler. The thermostat is configured to have 3 cycles (20min each cycle) per hour due to oil boilers not liking frequent cycling, 6 cycles is for Gas

... which is essentially the problem, the HP should control the HP!

Posted by: @technogeek

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I have now changed the field option #2092 to option 3 so now when the Honeywell thermostat demands heat, the circulating pumps run continuously for that period and the compressor runs until it reaches the water law (weather comp) temperature and then either slows down or stops until the circulating water cools enough for it to kick back in.

This has now enabled me to reduce my weather comp curve to 35C @ 10C OAT to 45C @ -2C OAT, the house still gets to 21C and the Honeywell thermostat is practically demanding heat for 90% of each cycle time. The heat pump seems to be a lot happier and now draws 1.4Kw instead of 1.9Kw in electricity. Since adjusting at the end of March 2024 my COP now = 4.4 up from 4.15

& the bold bit solves the problem more or less.  Essentially the Honeywell thermostat is doing nothing most of the time and leaving it to the HP to sort itself out.

HPs work best with minimal or no external controls, balanced emitters and the weather compensation curve adjusted so that the HP delivers heat most or all of the time at the lowest possible temperature which results in just enough energy being emitted from the rads/ufh to balance the heat loss from the house.  Any departure from this will almost inevitably reduce efficiency.  Some external control to mitigate unexpected or intermittent solar gain (or other sources of heat) is usually necessary, but configured as a limiter not a primary controller. 

A heat pump which is primarily controlled externally (other than by something like homely which is specifically designed for heat pumps) will almost certainly be an inefficient heat pump.