Heat Pump low pressure oddities

[tedsar]

Hi after doing a search on the forum, I didn't see anything specific to my issue. The situation is that since our pool was finished in late 2019, we have only ever been able to use our heat pump in 1 of 3 settings:
1. Spa only
2. Spillover only
3. Funky custom dialed-in mix of mostly spillover and bubblers

It will run in these 3 configurations only if the cartridge filter is clean.

My first thought is there is either a blockage or too much backpressure. Could you have a look at the picture and give your thoughts? I can take measurements as needed.

https://www.dropbox.com/s/053n8b62id9xc92/screenshot_20220424-111913_gallery.jpg?dl=0

Thanks,
Ted

[Denniswiseman]

If the filter is dirty then you won't get a good flow which the heat pump requires
Why didn't you address the problems when you had the pool installed?
How often are you cleaning your filter to get it to work, there could be underlying problems with your water

[Teapot1]

Seconded! Listen to Dennis.

[tedsar]

Regarding why these problems were not addressed during the build- the pool builders actually ended up in jail for fraud. Sadly, we only discovered the issue after the inspection, which is after we shelled out $20k over contract to complete the pool.

Regarding the water quality- when it is stable during the summer, I clean the filter every 2 weeks or so.

Pulling the filter and trying to run the heater doesn't change the operability of the 3 options I noted above. So, with taking the filter out of the equation, do you have any other suggestions?

Thanks

[Denniswiseman]

Cleaning the filter every two weeks seems excessive
Is it clogged when you do it?
Let's have your numbers (CYA is very important) Use a pool store if you don't have a FAS/DPD kit
FC:
TC:
pH:
TA:
CH:
CYA:

[tedsar]

Cleaning the filter every two weeks seems excessive
Is it clogged when you do it?
Let's have your numbers (CYA is very important) Use a pool store if you don't have a FAS/DPD kit
FC:
TC:
pH:
TA:
CH:
CYA:

I'll bring my water to Leslie's today and get the readout. Pardon my ignorance, but does water chemistry affect the pressure at the heat pump?

Thanks,
Ted

[Denniswiseman]

It won't affect the flow at the heat pump but the filter will if it's clogged
Water chemistry will determine why your filter needs cleaning every fortnight. When you clean it does it look clogged

[tedsar]

It has a slighly dark, discolored look to it, but I wouldn't call it clogged. For reference, when the pump is at 100%, with a clean filter (or even no filter) the gauge reads 18psi. When I pull the filter for cleaning it may read 26 psi.

[Denniswiseman]

Will the heat pump work okay with no filter or when clean
18 seems a bit high for a clean filter, when turned off does it go to zero

[tedsar]

Cleaning the filter every two weeks seems excessive
Is it clogged when you do it?
Let's have your numbers (CYA is very important) Use a pool store if you don't have a FAS/DPD kit
FC: 0.13
TC: 0.13
pH: 8.3
TA: 131
CH: 237
CYA: 29

I've started adding acid to bring the PH back in range.

[Denniswiseman]

Your chlorine is very low are you sure you don't have algae
Your spa spillover will increase your pH and the acid will bring down your TA which will help stabilise your pH

[Teapot1]

How large is your pool? 1.8thp is a heck of a lot, as is running at 18psi. That is a lot of back pressure which is a lot of dynamic head or friction. It costs you a small fortune in electricity and achieves nothing. If that is to give you great spa jet force its ruining your filtration. Slower filtration is better filtration and uses a fraction of the electricity and as the system spends most of its time in filtration I suggest some modifications. A variable speed drive for the pump and a separate pump without filtration just for the spa jets. What do you think? I have done similar for a customer and water quality improved, spa jets improved and electricity bill reduced by 90%.

[tedsar]

Your chlorine is very low are you sure you don't have algae
Your spa spillover will increase your pH and the acid will bring down your TA which will help stabilise your pH

My pH is now at 7.2, so I can start removing phosphates, sanitizing, and chlorinating. The pool person said my filter may need to be replaced, but if the pressure is the same with or without the filter, than maybe not?

How large is your pool? 1.8thp is a heck of a lot, as is running at 18psi. That is a lot of back pressure which is a lot of dynamic head or friction. It costs you a small fortune in electricity and achieves nothing. If that is to give you great spa jet force its ruining your filtration. Slower filtration is better filtration and uses a fraction of the electricity and as the system spends most of its time in filtration I suggest some modifications. A variable speed drive for the pump and a separate pump without filtration just for the spa jets. What do you think? I have done similar for a customer and water quality improved, spa jets improved and electricity bill reduced by 90%.

I had the same thought about pump size. For what we have it seems overkill. I typically run the pump during the day at 70% in a couple different modes. Unfortunately the heater won't run at less than 100% or close to it. We have a blower so jets aren't an issue.

[Teapot1]

Thank you for the update. Yes definitely overkill on the pump but the heat pump wont run without it. The heat pump will use either a pressure switch or a flow sensor. There is probably the problem. What does the manufacturer say? That is where I would go for information, maybe you can get a lower range pressure switch or flow sensor? When I built low energy pools using 90% less electricity I ran into salt chlorinator and dosing pump problems as the pressure on filtration was only 0.5-1psi so I often had to fit different sensors, not a problem just something I had to modify.
On yours with no filter the pressure is 18psi? That sounds like a valve not being fully open, it see you have a number of actuators so worth checking or some other horrible restriction somewhere. With variable speed pumps its a good idea to have a flow meter in line, something like the FlowViz is good as you can mount them anywhere pretty much. Then you can see what flow you are getting, which by the way doesnt sound like much. Well done for using air for the spa jets, so much better than trying to use water.

[tedsar]

According to the parts diagram for my heat pump, there is a pressure switch (HPX2181) mounted on the control board. I wonder if the hose going to the switch is kinked or has sediment from early on that's impeding the water? I'll take it apart and do a quick check that the line is clear and that switch is clean. Based on the error I get on the heat pump, it's acting like the flow isn't high enough, so would they be converting pressure to flow?

**UPDATE**
When I removed the control cover for the heat pump and looked at the pressure sensor, I discovered that there's a thumbwheel sensitivity adjustment. When I backed it out, the low pressure/flow warning went away and now it works in all modes!!!