Heater leak question - Only happens with valves set to spa and not pool

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philipaby

Bronze Supporter
Feb 5, 2020
16
Katy TX
Hi!
This is my first time on this forum, so unsure if I'm posting in the right place. But giving it a go. I have a Hayward H400 heater that I can use to heat up either my spa or pool. When I need to heat up the pool, I ensure the valves take in water from the pool and send it back to the pool and set the heater to pool mode. With spa, intake from spa, flowing back to spa and heater mode set to spa. Regardless of heater operation, water from the pump always flows through the heater (as is normal I guess). Interesting thing is that when the valves are set to pool, water flow is all fine, but when I get it to spa, water leaks out from the side of the heater. The leaks are not just drips, but a shower like flow. I'd talked to my pool guy about why the difference and he states that with the spa flow, the pressure might be higher (smaller intake and outflow) cause something in the heater to leak while with the pool the pressure reading is not as high. (This pressure is actually reflected in my main filter).

Not sure if anyone has experienced this before? Thanks in advance for your help.

Aby
 
Welcome to TFP.

What is the difference in your filter pressure when in POOL or SPA modes?

Post pics of your equipment pad and plumbing and valves so we can see what you have.

Please create your signature with details of your pool.
 
Do you have a variable speed pump?

Does the pump run at different speeds depending on whether it's on Pool or Spa?

The heater has some sort of damage that needs to be diagnosed and fixed.

When you turn the pump off, can you hear air getting sucked in at the heater?
 
Hi all,
Thanks very much for all the responses! Really do appreciate the help.

@ajw22 Thanks for the welcome! I don't remember the pressures off the top of my head and will post pictures of the setup when I get back home.

@JamesW, single speed pump is what I have, so speeds are the same where pool or spa. When the motor is switched off, I do not hear any air getting sucked in.

@swamprat69 the pool and heater setup came with this house and the records show they were installed in 2007, so am guessing 12 years old. The leak is happening on the side of the heater that has the water connections. Additionally, this is a saltwater pool, so could be that the internals of the heater gets more abuse than the normal pool?
 
I have a 14 yr. old H400 that developed a leak at the water header connection to the heater last winter. It turned out to be the header O-ring that was the problem. It probably happened because of the age of the O-ring and thermal contraction due to the lower temperatures (although a higher pressure could also have an effect). If you remove the plate that covers the water header connection, you may be able to determine if the leak is between the the header and the metal of the heater. If it is and you try to replace the O-ring make sure that you get an OEM (Original Equipment Manufacturer i.e. real Hayward part) O-ring as there are some labeled with the Hayward part number from sources such as Amazon that are sized (diameter) incorrectly and will not seal. I made that mistake myself and had to do the repair twice!
 
Thank you @JamesW and @swamprat69. Higher pressure might indeed be the culprit based on the pics attached here. And that seal you mentioned could very well be it. In the first pic, you can see the normal setup whereby water flows in completely from the pool and goes back mostly to the pool and a little to the spa (highlighted in the circles). Pressure hovers at around 20 psi. Once I switch the valves to fully intake from the spa and fully send back to the spa, the pressure jumps to around 27-28 psi and the last pic shows the water leak from the heater as soon as I did that. My heater is close to the age that @swamprat69 mentioned, so that header O-ring might not be able to handle the higher pressure. I guess question is whether the spa flow is ok to be at 28 psi.
Full disclosure, I'm not a competent handyman, I mean I have replaced the pressure switch and so on, but when it comes to working with pipes, I lean on my pool maintenance dude and he was not sure about the 28 psi. But then again he did state that he has not worked with heaters much, hence the reason I'm posting here.

Thanks again in advance for your help and patience!!
 

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28 psi is probably too high.

I suspect that there is some sort of blockage happening.

Maybe the check valve flapper has broken loose?

The leak looks like it might be from the drain plug underneath the header.
 
Actually Ted (pool dude) replaced the check valve flapper thinking that might be it, but still no luck. I will talk to him tomorrow and ask about looking at the header for the seal and the plug. Will report back depending on what we find. Thanks @JamesW and have a good night!
 

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Hello everyone,
Apologies for the really late response on this, but right after the last post on this, my motor started giving out, which required a replacement. Since that work was going on, I'd postponed the fixing of the heater leak. Switched to a variable speed motor while keeping the old pump. Interestingly, due to the piping layout for the setup, the old pump had this really large protrusion on the end of it's cover which made it difficult to sit properly on the new motor. Ted had to use some creative thinking to make that cover sit properly. After a week or so, the pump started to leak. At this point, we figured that we could either try fixing the leak methodically, or maybe replace the pump. Which was done. Moved to a hayward super II pump. While doing that, also replaced the O rings on the heater like @swamprat69 indicated. Pleased to note that there seemed to be no leak from the heater after that!

Thanks once again to all for your responses and lending your expertise in solving this issue. Much appreciated!

Aby
 
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