TK-2 - Water leak from pressure valve.

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Mweiss

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I have a Takagi TK-2, about 8-9 years old. It has had a few issues including a few cleaning after initial install for the typical scale build-up and a valve replaced after a few years. Other than that, it's worked great. I have a closed-loop recirculation pump to keep hot water close to the outlets in the house, so that means it runs longer over the course of it's life, the trade off to saving water.

For the past few months, there has been a small drip from the pressure valve outlet. I thought it might be some sort of condensation, but it has increased quite a bit recently. I suspect the pressure valve itself may be going bad and have a plumber scheduled to have a look. At the same time, wanted to ask if there is anything within the unit that might cause the constant drip past the valve. I have no evidence the valve has ever completely opened due to a pressure rise.

Is there something that might be building up excess pressure very slowly but steadily to gently bypass the valve? I think if I replace the valve and it stops, I'm still safe, and if it continues to leak, then get the more expensive service call from the Takagi tech.

Thanks-

Matt
 

Reach4

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Most commonly, that means that the expansion tank has failed and has become waterlogged. They are replaceable. They are fairly generic -- no reason to get that from Takagi. If you knock on the side of yours, it will probably sound full of water. The new one will be pretty much empty and will sound hollow when you knock.
 

Mweiss

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Most commonly, that means that the expansion tank has failed and has become waterlogged. They are replaceable. They are fairly generic -- no reason to get that from Takagi. If you knock on the side of yours, it will probably sound full of water. The new one will be pretty much empty and will sound hollow when you knock.

First off, thank you for the timely reply. A couple follow-up questions if I may...

Is the expansion tank internal and part of the unit or a an external add-on, as your "generic" description seems to indicate? I do not have (at least to my knowledge or obviously visible) an external expansion tank, there is simply a tee off the outlet line to a pressure valve which dumps outside the wall it is mounted on.

Sounds like what I am looking for is the place/component internally that would leak and fill the expansion tank, or in this case cause a very slight bypass of the pressure valve. Any thoughts what that internal component is and it's serviceability by a DIY or general plumber?

I'm not opposed to getting a certified tech out, but the last guy tried to sell me a new unit well over a year ago, and until this latest episode, the thing has worked great... Who knows, maybe he was right.

Finally, just to ask, is it prudent after 8-9 years (with a nod toward the circulation pump adding service time), to just replace the thing and move on? If it's getting to the point of it's life being run, better to do it now and be done with it than risk flooding the garage.

Again, thanks for the advice... Very valuable and very much appreciated.

Matt

Matt
 

Reach4

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I was presuming an external unit. If you don't have one, I expect you need one. To be sure, get a pressure gauge. If you see the pressure rise over 80 PSI at times, you would need a tank. If the water rises to over 80 while you are consuming water, you would need a pressure regulating valve and a tank.

Gauges for the purpose are easy to get and are under $20. The easiest to use are those with a garden hose thread connector. Ideally you will get one with a peak indicating hand (lazy hand) so that you don't have to watch the gauge. Watts Model # DP IWTG is an example of such a gauge.
 

Mweiss

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I was presuming an external unit. If you don't have one, I expect you need one. To be sure, get a pressure gauge. If you see the pressure rise over 80 PSI at times, you would need a tank. If the water rises to over 80 while you are consuming water, you would need a pressure regulating valve and a tank.

Gauges for the purpose are easy to get and are under $20. The easiest to use are those with a garden hose thread connector. Ideally you will get one with a peak indicating hand (lazy hand) so that you don't have to watch the gauge. Watts Model # DP IWTG is an example of such a gauge.

Incoming or outgoing pressure, or should there be no difference?

The dribble from the relief valve pipe is constant, which seems to me would fill an expansion tank quickly and I'd have the same problem. Is there anything that could fail within the unit to cause a pressure rise... or maybe my thought this morning is correct, that the relief valve itself is faulty, maybe from constant heat as it's very close to the outlet or some other issue.

Again, I appreciate the input, it is very helpful and I feel I am narrowing things down.

Thanks-

Matt
 

Reach4

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I am thinking it would not normally matter.

If the dribble is really constant, then the problem would probably be a problem with the relief valve. Here is a test: dribble a faucet a little more than the valve dribbles. If the flow from the valve stops, then it is probably that you need an expansion tank. If the valve still dribbles, it is going to be a leaky T+P valve.

In either case, I would get the gauge.
 

Mweiss

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That sounds very logical. I have a plumber I trust, but not a Takagi tech scheduled to come by and have a look.

Thank you so much for the remote analysis, again, REALLY appreciated that you are providing this help.

Matt
 
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