Strange hot water valve problem?

Every once in a while, probably every couple of days, when I first turn on the hot water in the house, there is very little pressure. But if I wait about 5-10 seconds, I hear a fairly loud "thunk" sound, and then the hot water starts to flow. I suspect there is some valve that is a bit stuck and the eater pressure forces it open or something. Anyone have an idea where I can locate the problem?

You have to isolate the problem, find out which fixture makes it happen , if all of them you have to inspect the piping there might be a bad check valve or prv .

SME-Subject Matter Expert said:

It turns out that sometimes you have to replace your hot water valve. You should never attempt to do plumbing experts are able to provide water heater valve replacement services to those in need. The company has thousands of good reviews.

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The OP is located in Toronto.
What valve, specifically, are you referring to as the hot water valve?

SME-Subject Matter Expert said:

It turns out that sometimes you have to replace your hot water valve. You should never attempt to do this task on your own. Plumbing experts are able to provide water heater valve replacement services to those in need. The company has thousands of good reviews.

Click to expand...

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Diehard said:

The OP is located in Toronto.
What valve, specifically, are you referring to as the hot water valve?

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I meant it as a question, as I have basically no knowledge. Is there some kind of valve and are there any suggestions of where to look? All I know is that at more than one tap, the flow will be little more than a trickle, then a "thunk" sound from somewhere in the house (probably downstairs) and then it runs fine. So, I just assume it is some kind of valve or regulator.

Rob98765 said:

I meant it as a question, as I have basically no knowledge. Is there some kind of valve and are there any suggestions of where to look? All I know is that at more than one tap, the flow will be little more than a trickle, then a "thunk" sound from somewhere in the house (probably downstairs) and then it runs fine. So, I just assume it is some kind of valve or regulator.

Click to expand...

Sorry...my comment was not meant for you but to "SME-Subject Matter Expert".
As mentioned in comment #2 above, you can try isolating the cause by finding out which fixture use causes it and which if any do not.
In other words, if you could work back to a valve(or valves) that was feeding those fixtures that have that problem, you'd have a better chance of possibly finding it.
The fact that it's only the hot and not the cold water would seem to me that it wouldn't be a PRV which I assume would be feeding both hot and cold water uses.

I don't know if you have any globe valves but they could have a washer that can get loose
Do you have any type of temperature control valve/mixing valve at your hot water source?

The CW valve feeding your water heater cannot be excluded from the possible cause.

So I repeat, you are looking for any valve or device that feeds ONLY those fixtures that have those symptoms. Then you might want to have someone cause the event while you are at one of those possible candidates, with your hand on it.

Rob98765 said:

I meant it as a question, as I have basically no knowledge. Is there some kind of valve and are there any suggestions of where to look? All I know is that at more than one tap, the flow will be little more than a trickle, then a "thunk" sound from somewhere in the house (probably downstairs) and then it runs fine. So, I just assume it is some kind of valve or regulator.

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Mr Rob, their are many different types of water heater systems
from the info you have given,,I can only shrug and say ''I dunno''
Can you provide a picture of the water heater and the piping so we can see
what you have...

I'm with Frodo (again jeez Frodo's always right...) on this issue, too many unknown variables. I would also check if a backflow preventer insert in the nipples on top of the water heater is sticking shut.

Another question for the OP...do you have a recirculation loop for your hot water?

SME-Subject Matter Expert said:

Yes, the hot water valve.

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If it is with the same valve, I.e. the bathroom sink, sometimes the washer is loose and sticks to the seat for a few seconds until the pressure pops it open. Just a thought.

Start at the HW valve closest to the water heater and see if the thunk! happens. Work your way along the line to find the first valve that shows the problem. The problem is somewhere between the last 2 valves. Another question - after a thunk!, if you turn off the valve that caused it, do you get a new thunk! if you turn on that valve immediately, or do you have to wait a while?

Every once in a while, probably every couple of days, when I first turn on the hot water in the house, there is very little pressure. But if I wait about 5-10 seconds, I hear a fairly loud "thunk" sound, and then the hot water starts to flow. I suspect there is some valve that is a bit stuck and the eater pressure forces it open or something. Anyone have an idea where I can locate the problem?

a globe valve with a loose bib washer