Pool Heater Stopped Working on Low Speed

[panamax53]

1.My Jandy pool heater was working fine on the low speed cycle of my 2 speed Jandy pump. I noticed yesterday the pool getting colder and discovered the pump not running on the low speed cycle. The digital message reads "No Flow". I know the bypass is off and all the flow is going through the heater. When the heater was installed late summer they had the bypass valve set to 1/4 open. In that position the heater would not function on low speed. With the bypass valve closed it worked fine. There is a round clear plexiglass cover over a red backflow preventer valve. (I think that's what it's for). That flap can be seen to be horizontal indicating a pretty good flow. The filter was just cleaned.

Is there a flow sensor that goes bad?

2. Does this heater, model listed in signature, have copper coils that will eventually deposit copper stains into my plaster later? If so, what do I do to prevent it?

 

[bdavis466]

Not sure on your model but most heaters and heat pumps use pressure switches (not flow sensors). I'd check that first as an obstruction can easily cause this issue. Does the heat pump have flow issues on high speed? Are you certain your filter is clean? Has the heat pump ever had issues on low speed previously?

Just about every heater or heat pump has copper in it somewhere. This is not an issue so long as your water chemistry is kept in line. Out of balance water has killed many heaters/heat pumps and could very well have contributed to your issue.

 

[SacPoolPros]

If heater was working before on the low pump speed more then likely your filters are just dirty and need to be cleaned

 

[panamax53]

Heater installed late July 2015. Pool Company maintained pool from Aug 8 until early Nov when they fired me as a customer. They did not want to raise CH to the 200 - 400 range. The CH was not budging from 140. I asked too many questions that went unanswered. Whenever I've added Calcium it went up to what I predicted and did not inch higher at all.
FC 7 (coming down after slamming a week ago)pH 7.7, CYA 75 ish , CH 350, TA 60, Salt 4200-4400ppm.
Filter wasn't too dirty, but was cleaned 7 days ago. Still clean. No previous issues.
So, let's assume it's a pressure switch issue. Would that be a warranty issue? Is there a way I (not a particularly handy guy, but not stupid) could check it out? Or, would that jeopardize the warranty?

 

[Bama Rambler]

It could be some debris in the pump impeller causing low flow (i.e. low pressure) and therefore not allowing the heater to fire.

If it still works on high, my bet is that it isn't the pressure switch.

 

[duraleigh]

Has your low-speed psi changed?

 

[pooldv]

+1 on cleaning the filter to fix the low flow issue.

A comment on CH. The CH will continuously rise over time as water evaporates leaving behind the CH and adding more with the fill water. This can be a long, slow process or can happen quickly depending on what your CH is in your fill water. So, be careful with raising CH too much up front.

I do agree with raising CH from 140 to 250 or so. I also agree with firing the pool company no matter how that happened.

 

[panamax53]

Duraleigh I figured it out on my own. Came to recall I turned my shears on last week at TFPs recommendation when shocking. That reduced the flow enough so that at low speed heater will not function. Even South Florida gets cool and my wife wants to swim in 87 degree water. I think it would be cool to know what my flow rates are since the SWCG has a range of 40 to 92, the heater from 20 to 70 with 40 being optimal and god knows what the MX8 cleaner wants. Suggestions? Should have gotten a VS pump. May still go there if I can get some money for the old one. Heck its only been operating 5 months. The SWCG only will run on the hi speed side. Boy that would be great to tweak a VS pump to just over 40 gpm and get the heater and swcg to work! I'm guessing I'm not near 40 when on hi speed and I know I am far from it on low speed
Pooldv you have it backwards. They "fired" me as a customer. I asked too many questions and wanted my CH raised above 140 to at least 200. Calcium is expensive and don't worry about balancing. So I found TFP and am much happier. My Calcium level is pretty low here so refilling hasn't created an issue. Have had to drain on a few occasions too. I keep a close eye on it and only recently raised to the minimum TFP recommendation for SWCG pools.

 

[pooldv]

Good news! Sounds like a good plan on the CH. It is definitely nice to have a VS pump to dial in the right flow for all the different stuff that needs water flow.