Heat Pump Sizing?

FreeBear

michaels said: Heat meter temp probes not giving reliable readings (1 in pocket, one taped to pipe) so need to estimate output based on heat pump reported flow and return temp and heat meter reported flow rate rather than having actual readings

Using a thermal pad between the loose sensor and pipe then wrapping a bunch of insulation over it will improve matters a bit. Ideally, the sensor should sit in a thermal well so that the tip is on the centreline of the pipe - I used a 22mm branch tee & thermal well for mine.

michaels

FreeBear said:

michaels said: Heat meter temp probes not giving reliable readings (1 in pocket, one taped to pipe) so need to estimate output based on heat pump reported flow and return temp and heat meter reported flow rate rather than having actual readings

Using a thermal pad between the loose sensor and pipe then wrapping a bunch of insulation over it will improve matters a bit. Ideally, the sensor should sit in a thermal well so that the tip is on the centreline of the pipe - I used a 22mm branch tee & thermal well for mine.

I think I can install it in a ball valve like this:

3/4" BSP (DN20) Temperature Sensor Ball Valve – Stockshed® | the meter company - A GLAD Group Company.

22mm Test Point Ball Valve | Direct Plumbing Supplies

FreeBear

michaels said:

FreeBear said:

michaels said: Heat meter temp probes not giving reliable readings (1 in pocket, one taped to pipe) so need to estimate output based on heat pump reported flow and return temp and heat meter reported flow rate rather than having actual readings

Using a thermal pad between the loose sensor and pipe then wrapping a bunch of insulation over it will improve matters a bit. Ideally, the sensor should sit in a thermal well so that the tip is on the centreline of the pipe - I used a 22mm branch tee & thermal well for mine.

I think I can install it in a ball valve like this:

3/4" BSP (DN20) Temperature Sensor Ball Valve – Stockshed® | the meter company - A GLAD Group Company.

22mm Test Point Ball Valve | Direct Plumbing Supplies

The first one looks like a malleable iron fitting for screwing on to threaded pipes.  By the time you've purchased a pair of male couplers, it gets quite expensive.

The second one is for gas pipes, so the test point will (probably) be wrong.

https://themetercompany.co.uk/products/p-sx could be useful (or a longer version) coupled with a branch tee.

michaels

At these outside temps we are definitely seeing the impact of undersized rads.  In order to output enough energy we are having to run the rads hotter, the larger water to air delta T means more heat is transferred from the water so we get a bigger flow and return gap.  This higher water flow temp translates directly into higher consumption for the same energy production.

The 'Heath Robinson' set up means we are losing 3 rads worth of output due to where the heat pump is connected into the hearting circuit and my DS insists on having his room cold for sleeping so that is another large rad turned off, so probably about 20% of rad capacity is out of action.

By my calcs I would need to change 9 rads to reduce the max flow rate by 10c, a project for next summer I think!  I wonder if it could possibly pay for itself, our leccy is currently only about 8p per unit so savings from increased efficiency are small.

michaels

We had a brown out on the leccy today, not really noticeable but for example it reset a TV set top box and a microwave clock. 

Unfortunately it was also enough of an interruption to turn off the heat pump, as I mentioned above it does not seem to remember settings when power cycled and restarts in heating off mode with also a 'holiday' programme set and of course the time lost.

Anyone know where I can go for support?  It is an LG Therma V 12kw U32 model.  If it were a PC you would say that it needs the bios battery replacing.

Thanks

Reed_Richards

I have an LG Therma V heat pump.  I'm not aware that it is possible to set a "holiday programme" but we've been here before without a resolution.

michaels

Thanks

I have this controller which is one of the oldest ones:

There are about 3 or more newer generations since.  I don't think it is possible to simply use a newer controller with the older hardware?

I think you uploaded this image of the circuit board of a newer model and I think there might be a battery round about 1/3 from the bottom and left of the image but ours has a different circuit board. (LG Therma V mono block Air Source Heat Pump - Page 13 - Other Heating Systems - BuildHub.org.uk)

Reed_Richards

I don't really want to prise open my controller to see if the circuit board has a battery.  My newer LG heat pump certainly remembers all its setting after a power outage but whether this is due to volatile memory and a battery or just non-volatile memory I don't know.

michaels

I think my image is the internals of this one:

Reed_Richards

Yep, that's the one I've got.  But the only benefit I can think of in having volatile memory and a battery is that as a last resort you can wipe the memory by removing the battery.  Whilst the downside is that the battery will not last forever.

Anyway, if the new controller does have a battery then it's very likely that the old one does to and it is designed to be removable from the mounting plate.  So you should be able to do that and look inside.