Heat pump vs electric heater for a UK pool

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I was confusing I think. Just look at the main pump, and if there's a plate on it with numbers, take a picture of it. I'm looking for brand name of the pump, model number if it shows, and HP (both figures if there are two). Thanks

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Your equipment pad looks good!
 
Your pump is a Sta-rite 1/2 HP. The links below include the manual and a brochure
http://www.allswimltd.com/pdf/1044-5P2R%20Manual.pdf
http://poolstore.co.uk/upload/photo/cms/file/pdfs/starite.pdf

Flow looks to be fine for your proposed heat pump, but tell me your filter pressure. There's a gauge between your multiport valve (the thing with the big handle) and the filter body (blue). When the system is running, what number is the needle pointing to? And what units - could be something like PSI, KPA, M head, or Ft head.
 
At 1.4 bar (about 14.3 metres head; 20 PSI) your pump should be doing just a hair below 5 cubic metres per hour. That's very likely close enough that your heater will run fine, but I wouldn't worry about that until a few things are checked.

The gauge can be old. One way to check is - does the gauge read 0 when the pump is off?

Normally, just after backwash, you record the pressure and that is known as your clean pressure. Over time as the filter gets dirty, the pressure rises. When it's around 25% higher than the clean pressure, that's when you backwash. Does this all sound familiar to you? If not, we can walk you through it.

Is your filter dirty just now? What is the pressure immediately after a backwash?
 
I don't think this is going to be what you (and therefore I) want to hear.. but yes when off the needle is on 0. Then up to 14 during use. During a backwash its down to 10.5 and then after a 20 second backwash and 10 second rinse (basically until the water in the sight glass was running clear) it was still running at 14. There appears to be no clean pressure...?!
 
Gauges often have two scales, one inside the circular line and one outside the circular line, and two units. I mentioned it because 14 bar isn't possible. 1.4 bar is possible or 14 PSI is possible. Have another look at that.

20 second backwash is much shorter than mine. I do about 1.5 minutes backwash and around the same for rinse.

If we're still stuck, there are some other things we look at to reduce backpressure. Last resort would be a slightly larger pump (or perhaps just the pump motor, we can check that later) to get the higher flow rate.
 
One bar means one atmosphere of pressure, or a bit over 14 pounds per square inch (PSI). So 14 bar would be 200 PSI, and residential pools run up to a maximum of 50 PSI, the common maximum working pressure rating for the equipment. Typical pressure for a single speed pump and filtration system would be somewhere between 10 and 30 PSI.
 

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Same pressure before and after most likely means that it was already clean before backwashing, and you can note 14 PSI as your "clean pressure". Wait to backwash until it's 20 to 25% above clean pressure. You'll find that it filters better when it's a bit dirty.

There's a remote possibility that the sand is channelled, but if your pool is clean I doubt this is the case. Besides, 14 PSI makes sense for your setup.

The good news is that you have plenty of flow for the heater. At 14 PSI it's roughly 7 cubic metres per hour and at dirty pressure of 18 PSI it's roughly 6 cubic metres per hour.
 
So the lower the psi the higher the flow rate? Thank goodness for that. I went back through your post and saw that if 20psi is 5m3/sec and wrongly assumed that 14psi would be around 4m3/sec.

I can't express how grateful I am I feel so good knowing there is such a wealth of information available here as this is all new to me and I'm lacking in some confidence on all things pool to say the least! Thank you so much.

I now need to move my thoughts to the installation. A family member is an air conditioning installer and he said he'd fit it with me. Is it as simple as draining and cutting the pipe after the existing heater (I'm going to leave it in line as a spare) and adding in the loop for the heater (with an additional isolation loop for removing it if necessary)

I'm going for 2" pipe to try to reduce friction heat loss and I have my neighbour doing the electrics as he is the electrician that originally set the pool up.

Any tips or things to look out for on the installation front?
 
Yep, if the pump is using more of it's power to overcome friction loss, it will have less power available to move water. Happy to help.

Note that it's cubic metres per hour (not second :))

I'll leave the plumbing to others who've plumbed more heaters. I'll put out word to a couple people if need be.

Good idea keeping the original heater as well. Reason being that real-world coefficient of performance (CoP) from a heat pump seldom matches the "marketing" performance. As the outside air gets colder, heat pump performance drops, so average performance is lower than the flashy marketing CoP. And of course you heat a pool the most during shoulder seasons when outside temps are lower. Also, it's running at night some of the time, when air temp is lower. I still think it's a good choice for you economically, but don't know anything about the brands and such. Your original question was about whether to expect the CoP of 5 (or 1/5 the electricity as compared to your resistance heater). If you only run it during the day and when air temp is near 25C, that's possible, but I think it's too optimistic for calculating potential savings. An average operating CoP of 4 would be more realistic, in my opinion.

Have fun with your nicely heated pool! :)
 
Per hour.. noted. haha

yeah I've lowered my expectations to CoP of 4 after hearing what people have said. Still seems like a very good investment to me.

Not being as fortunate with the weather as you i'd more likely heat it during the day (because of air temp) and around the time i'm going to use it (when temps rise to about 20 celcius plus) so hopefully I wont be fighting too much of a chill outside to get it heated.

I'll get the pump ordered! thanks again
 
Hi guys, so, the big install is this saturday. I have (I think) all of the required pipework, bends, primer and glue so wish me luck.

Before I go making a horrible mistake I just wanted to confirm I'm doing the correct thing to put the heat pump directly before the existing heater? There is a couple of right angles making a u bend which I'm hoping to cut off and extend out from there and that will be the run down to the heat pump. I can take a photo if necessary.

If somebody could confirm that I'm ok to just drain the pump like I would at close of season and then chop off directly before the existing heater and crack on, that'd be great
 
well, a few leaks at some of the solvent weld joins due to not twisting or champhering the pipe however, I have to say, the heat pump is one of my best investments to date.
the 14kw polytropic heat pump seems to heat at the same speed as my 9kw electric heater but at a quarter of the price. It isn't anywhere as loud as I suspected and the fact we have run it to the far (hidden) end of the pool sheds was a great move, you'd barely know it was there. I couldn't be happier and we have finally got to use our pool regularly (6 days in a row and counting!!) thanks to all for your advice.
 
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