Chinese Hydronic Heater Troubleshooting Resources?

[ckouba]

I know this question has already probably been asked, so I spent a couple of hours on here with the Search function. Unfortunately, that has proved fruitless, so I am posting the question for the collective brain trust.

I am installing a Junyize 5kW diesel "parking heater" for a hydronic system. It seems to fire up and heat up just fine but the coolant pump does not run as I would expect it to- it cycles for about 45s of running then shuts off for about as long. The heater then throttles back (as it should) when it nears the set point of 80° C, and then shuts down because it's not circulating unwarmed coolant through the heater body.

The pump does not seem to be able to push coolant around a very modest loop. I can see air pockets in the PEX tubing and they don't move with the pump. They do move when I squeeze on the hose sections, so I assume there's no flow constraint.

I did pull the pump from the system and checked its flow, and it made quite a splash in the kitchen sink, so I assume it's able to push something around. They are supposed to be able to push around a system's worth of coolant. The loop I have it valved off to right now shouldn't be too large of a challenge- maybe 12' of 1/2" PEX and 10' of 3/4" PEX and hose.

I have an expansion tank as the high point of the system (~5' off the floor). The line out from the bottom of that runs directly to the pump input, whose output runs directly to the heater input. I've run the pump with the tank in the high-mounted position and I've run it with the tank laying on the floor (to reduce the pump head required). No change in pump performance.

When I pulled the pump from the system. It ran with 12V applied. I only checked it briefly.

When I applied voltage at the pump after it was plumbed back into the system (but NOT plugged in to the controller- just my 12V power supply), it cycled like it did when it was being directed by the system controller (~45s on, ~60 off), which makes me wonder if there's something wrong with the pump. There is a PCB inside the pump but I can't tell if it was overheating- or at least it didn't feel warm to the touch.

Regardless, my main concern is that it doesn't push hard enough to move the coolant through the pipework even when it is running. Any suggestions for troubleshooting? Has anyone here dealt with this or something like it, or know someone who has?

Thanks in advance,
Chris

 

[highwest]

I’m sorry, I don’t have any advice for you, but have you inquired with the Chinese desire heater group on Facebook? They have a wealth of information over there.

 

[Toyaddict]

From what I know of geothermal loops you need a velocity of ~2fps or more to remove air bubbles from the system, I imagine this is similar. In hvac we achieve this by using a flush cart with powerful pumps. Sounds like a closed system do you have a way of bleeding the entrained air once you get it in one place, maybe I missed that part?

 

[ckouba]

I’m sorry, I don’t have any advice for you, but have you inquired with the Chinese desire heater group on Facebook? They have a wealth of information over there.

Not yet, had to apply to be let in, so I did last night. That's the next place I'll be checking in.

From what I know of geothermal loops you need a velocity of ~2fps or more to remove air bubbles from the system, I imagine this is similar. In hvac we achieve this by using a flush cart with powerful pumps. Sounds like a closed system do you have a way of bleeding the entrained air once you get it in one place, maybe I missed that part?

It is a closed system but I was expecting the expansion tank to take care of bleeding the air from the system. I don't have any ports on it where I can manually let any pressure out.

My biggest issue presently is that the pump doesn't continue to run when voltage is directly applied to its terminals. I can't imagine it's sophisticated enough to sense it's not pushing water and shutting down.

As I think about it, my biggest issue actually may be not being able to push the air through the network. Maybe solving that will resolve the pumping issue. Off to check the FB group.

 

[simple]

I've checked thermal cutoff stuff before with an infrared thermometer. You wouldn't be measuring an exact internal temperature but you could see if it shuts off every time the housing gets to a certain temp. If it has a thermocouple, the calibration could be off.

If the heater wasn't very expensive, you could buy another one and see what it does and determine if you need to send a faulty one back or find another solution and keep it for parts.

 

[lost1]

Could the air bubbles cause cavitation at the pump and then the pump runs "dry" creating a shut down?

 

[Peter_n_Margaret]

Not your immediate problem, but I reckon 1/2" pipe is way too small.
With my (German) hydronic unit, I can run an auxiliary pump to circulate coolant when the diesel heater is not running. You could put another pump into the circuit to see if that fixes the problem.
Cheers,
Peter
OKA196 motorhome

 

[ckouba]

Could the air bubbles cause cavitation at the pump and then the pump runs "dry" creating a shut down?

I could see that it would prevent strong enough flow to actually flush the bubbles, but I have a hard time thinking that a cheap pump in a cheap system would have that much functionality to auto-stop when running dry. It's a centrifugal impeller pump, so not sure it hurts to have it run dry. In the same respect, with the circuit board in there, it may sense that it's overspeeding and assume that it's dry?

I ordering a vacuum fill kit to get the air out of the system. Will see what happens after that.

Not your immediate problem, but I reckon 1/2" pipe is way too small.
With my (German) hydronic unit, I can run an auxiliary pump to circulate coolant when the diesel heater is not running. You could put another pump into the circuit to see if that fixes the problem.
Cheers,
Peter
OKA196 motorhome

Ugh. That's not fun news. The system is installed now so I will be going with it, but thankfully the interior is not yet finished so changes are possible. But they will be painful if needed.

 

[ckouba]

After a much more thorough bleeding (and putting on the clamp that I missed), the system is now performing better. It warms up and pumps coolant around as it seems it should. However, now, after some time running just fine, getting up to ~60°C, it shows E-14 and shuts down.

It has a troubleshooting reference for the codes, which conveniently skips 14. I have been all over the internet searching for it and only find the air heater code lists, and none of which are applicable. I've had no luck on the FB forums either.

Anyone here know what error 14 is on a Junyize coolant heater and how to resolve?

 

[Daviticus]

I haven't experienced an E-14 in my test runs yet, and of course (as you've found) the poorly-translated Russian/Chinese user manual doesn't list it and isn't clear anyway. I'm curious if it's another version of the burner overheat code, or perhaps something referencing exhaust temperature. I suppose it also could be related to the pump motor circuit, maybe the pump being bad is causing an open or short and the control unit isn't happy about it? I'm just spitballing at this point.

The circulation pump is a knockoff of a Bosch pump used most famously in the cabin heater systems of 2000s Mercedes Benz S-Class cars. I've grabbed a few from junkyards for my project. They're dumb pumps - they have zero control mechanisms built in, just power them and they work. It could be worth grabbing a genuine Bosch unit and plug pigtail (they are slightly different) and wiring it in to see if that makes a difference. I junkyard my stuff for proof-of-concept builds, but even new the pump is cheap.

 

[ckouba]

This was the reply I got from the manufacturer:

"Hello, E14 relay is connected, please check whether it has friction with the negative electrode of the body or water"

Didn't help me resolve it, and after all the monkey business, I will be moving up to the Euro brand. I need it to work, and if I have an issue, I want to be able to resolve it. It was a reasonable experiment to see if I could save a little $'s, but I am moving on. I have a trip with the wife in Feb so it needs to be running reliably by then.

I believe the pump from the system is a bit smarter than we realize. It would cut in and out based on hydraulic load applied even when the signal was telling it to run. It did this both when plugged in to the system and when I snipped out the harness and hard wired it.

...unless there was something bad with the board in the pump.

For the record, I also tried other pumps and same results.

 

[nelstomlinson]

I bought a Chinese Webasto air heater clone. It kinda works: it'll heat air, and it hasn't caught the place on fire...so far. The manual is useless gibberish. Youtube videos showing what looks like my controller show functions it doesn't have, like thermostatic control. It's not satisfactory. I'd have been better off spending 5 times more for the real thing.