Pentiar Minimax 400 - Cycling on/off every 5-7 minutes

[casastevo]

New home fellas, inherited a pretty old heater. It hasn't worked reliably since I bought the house. So far, I've:

1. Ran high pressure gas over, installed a regulator at the unit. Previous tech said line wasn't getting enough pressure. Probably good I did this anyway, even though it didn't fix the problem.

2. Replaced the hi-limit sensors (both of them).

The unit is in bad shape cosmetic-wise. Lots of rust, dust, dirt, all through it. I'm going to take some compressed air to it in the morning, but thought I'd share some pics and see if you guys could point out any other possibilities. Any help is greatly appreciated.

Images: http://imgur.com/a/2Oazt
Video of it shutting off (with buzzing noise): http://www.youtube.com/watch?v=7C6f12XLhRM

Update: Did more research on the forums here, looks like I may tackle the flow valve next. AND, uh oh. I have yellow flames, looks like I definitely need to clean it out per the maintenance instructions.

"Visually inspect the main burner and the pilot burner
flame. The normal color of the flame is blue. When
flame appears yellow, burners should be inspected
and cleaned; see Figure 10"

 

[ps0303]

How did the tech know that you didn't have enough gas pressure?

 

[casastevo]

How did the tech know that you didn't have enough gas pressure?

He had some sort of meter hooked up to it. Said the gas pressure at the line, heater off, was 4lbs/in and then when you turned the heater on, it was 2lbs/in. Heater needs at least 5-10 per the sticker inside.

Probably a waste of time though (and $750). The compressed air seemed to do the trick. It's been running for about 30 min now. *crosses fingers* Both our gas utility provider and the plumber I hired said that the length of pipe for the non-high-pressure gas was way too long, and the manual read that the pipe was also too small. Either way, looks like it probably needed to be done.

The flow valve manifold was still pretty cold, so I figure that shouldn't be problem. Wouldn't the manifold be hot if the valve was malfunctioning?

 

[ps0303]

He had some sort of meter hooked up to it. Said the gas pressure at the line, heater off, was 4lbs/in and then when you turned the heater on, it was 2lbs/in. Heater needs at least 5-10 per the sticker inside.

Probably a waste of time though (and $750).

He didn't charge that for telling you the pressure was too low, did he?

The compressed air seemed to do the trick. It's been running for about 30 min now. *crosses fingers* Both our gas utility provider and the plumber I hired said that the length of pipe for the non-high-pressure gas was way too long, and the manual read that the pipe was also too small. Either way, looks like it probably needed to be done.

The flow valve manifold was still pretty cold, so I figure that shouldn't be problem. Wouldn't the manifold be hot if the valve was malfunctioning?

The valve won't really be hot. You might feel some warmth though

 

[casastevo]

He didn't charge that for telling you the pressure was too low, did he?

Nope.

The valve won't really be hot. You might feel some warmth though

It's actually really cold when I touch it. Heater worked wonderfully yesterday though, so it looks like the problem is fixed for now. I was getting worried there, didn't want to get a new heater.

On the bright side, this 400k BTU heating is heating my tiny pool FAST. They totally went overkill on the BTU's when they bought this thing.

 

[ps0303]

Glad things are working. I wouldn't expect that unit to last too much longer. Hopefully you can at least get this seasons worth out of it.

Many people don't want to wait a long time to heat the water so they buy the biggest heater to get it done quicker.

 

[casastevo]

Glad things are working. I wouldn't expect that unit to last too much longer. Hopefully you can at least get this seasons worth out of it.

Definitely hope so as well. I'm eyeing the Raypak, 399k BTU heater for a replacement when it finally bites the dust. I'm beginning to be a fan of the oversized heater, and it barely cost me $15 to heat the pool over the weekend.

 

[Hawk]

I'm not sure how old your MiniMax 400 is, but mine has been running strong since 1996.
No repairs needed so far, knock on wood...

 

[casastevo]

Mine can't be more than 14 years old, but I bet it's up there. Great to hear yours is still kickin'! Do you do any maintenance on it? I figure an annual cleaning with compressed air and pipe cleaner would prolong the life a bit more.

 

[Hawk]

No, no maintenance at all. Most I do is turn the gas off to it during the off season. Heck, I'm not even sure if I should do that, but I have a shut off valve right where it enters the housing. I looked at your pics/video and I'd have to say mine is a bit dustier than yours inside, but not as much rust/scale laying at the bottom. Other than that, identical.

 

[casastevo]

No, no maintenance at all. Most I do is turn the gas off to it during the off season. Heck, I'm not even sure if I should do that, but I have a shut off valve right where it enters the housing. I looked at your pics/video and I'd have to say mine is a bit dustier than yours inside, but not as much rust/scale laying at the bottom. Other than that, identical.

That's interesting! This thing looks like it's built well, and the parts are cheap too. I really think the compressed air to the burners and heating element fixed me up.