Rinnai I-series tankless combi intermittent E430

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nhandojo

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Hello,

I have a fairly new (~8 months old) Rinnai that just recently started throwing E430 (low/high water pressure error). This happens intermittently when there's a demand for DHW or CH. It can be reset and the unit would work again for a few hours and then would error out again when there's demand for hot.

I can sort of trigger it to happen by inducing a large DHW demand, e.g. filling a bath, and I was watching the performance data display on the unit when this happen. The displayed water pressure is reading close to 0 PSI (it fluctuates when there's a demand for hot, but settles as soon as the unit reaches temperature), so I think the controller is doing what it is programmed to do, which is protecting the unit from boiling over when it thinks there's no make-up water. The trouble is, the external pressure gauges are all reading ~22-23 PSI, and there's no leak.

I had checked the circulator motor spins freely, DHW input filter screen is clean, CH filter is clean, etc. Any ideas what might be wrong? Should the boiler's internal pressure display dips below steady-state pressure when the boiler is activating? I can't think of the reason why this internal pressure gauge would dip low when the unit is starting to heat.

Thanks for reading,
Nick.
 

Fitter30

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E430 minimum 13lbs max 30lbs on the boiler side. Need to hook up a external gauge to the system. Possible one of two problems sensor is bad or expansion tank charge is wrong or bladder is bad. Fill pressure set the same as bladder pressure on a.cold to warm boiler.
 
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nhandojo

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Thanks for the insight, fitter30. I did check the expansion tank, and it is not waterlogged, though I haven't check its bladder precharge pressure with the tank isolated yet. Need to get a hose to be able to drain the tank without spraying water all over the place.

I suppose the only other thing to check is the pressure sensor in the boiler itself. There's an external pressure gauge on the supply side of CH loop and it reads a consistent pressure, 22-23 PSI.

Since this error happens also with only DHW active, I would have thought that the CH loop is not "in the loop", therefore isolating the problem to be internal to the boiler. Is this sane?

EDIT: forgot to mention, changing pump speed to low makes error more reproducible. Just as an experiment, the pump speed should be set to high as per Rinnai.
 

nhandojo

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Yes, I have the manual and am well aware of the steps the outlined there. The original installer agreed to come over on Tuesday and have a look, hopefully we can get to the bottom of this then.
 

Plumber69

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Hello,

I have a fairly new (~8 months old) Rinnai that just recently started throwing E430 (low/high water pressure error). This happens intermittently when there's a demand for DHW or CH. It can be reset and the unit would work again for a few hours and then would error out again when there's demand for hot.

I can sort of trigger it to happen by inducing a large DHW demand, e.g. filling a bath, and I was watching the performance data display on the unit when this happen. The displayed water pressure is reading close to 0 PSI (it fluctuates when there's a demand for hot, but settles as soon as the unit reaches temperature), so I think the controller is doing what it is programmed to do, which is protecting the unit from boiling over when it thinks there's no make-up water. The trouble is, the external pressure gauges are all reading ~22-23 PSI, and there's no leak.

I had checked the circulator motor spins freely, DHW input filter screen is clean, CH filter is clean, etc. Any ideas what might be wrong? Should the boiler's internal pressure display dips below steady-state pressure when the boiler is activating? I can't think of the reason why this internal pressure gauge would dip low when the unit is starting to heat.

Thanks for reading,
Nick.
Did you figure this out. Exactly the same thing is happening to me
 

John Gayewski

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Very first thing to do is call Rinnai. They might have a varified issue that they know about. I've heard of some with them. No specifics though.
 
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