MarkG

Does anyone know if an occasional slight drip from the pressure relief valve on the water heater is 'normal'?

When we first moved into the house last week there was a permanent puddle by the side of the heater because the valve was continuously leaking slightly, maybe a drop or two of water a minute whether hot or cold, even with the heater switched off. That was one of the things the inspector pointed out before we bought the place.

We replaced the valve (as far as I can see there was a bit of crud preventing it from closing fully) and that stopped, but the new one still drips slightly while the heater is running after I have a long shower. A short shower or normal heating use (e.g. after filling a sink with warm water) seems to be fine.

The manual mentions that you should expect condensation on the water tank if a lot of cold water goes in there at one time (and I can see that dripping out onto the floor underneath), but I don't see how that would come out of the relief valve. And the amount that does come out is nowhere near enough to relieve internal pressure if there really was a problem that was forcing the valve to open... it also seems to be cold water although the valve itself is warm to the touch, so may be condensation from somewhere rather than water from the tank.

Of course the manual also says that the heater should be installed with a drip tray underneath to direct condensation to the nearest drain, which the builders didn't do... and I can't see any way of lifting the tank to install one now. Grr!

Alternatively, maybe I just need to take shorter showers .

hot wasabi peas

A while back I had a home inspection done on a new home and the inspector pointed out a similar thing... a slight drip from the safety valve. I said something along the lines of 'but it's new' and he said that sometimes all it takes for them to start dripping is for someone to open and shut it. He said many times the valves just never shut back up properly... even if they're new.

Or somehow the pressure in your tank is getting a little high.

That's all I know about safety valves.

Souvenir

Get it looked at by a plumber and, if necessary, replaced (they're not hugely expensive). You do not want a leaking water heater, I can assure you. Ours developed a tiny leak, probably a rust hole the size of a pinprick. In one night it caused enough damage to require a $7,000 re-furb of the basement.

Steve_P

I agree with HWP, once opened it is very difficult to get them to re-seat, usually it it easier to replace it. If you do it yourself don't forget to put teflon tape on the threads before you install it.

Something else that might be worthy of checking is the water pressure, if that is high to begin with heating the water will only add to the problem.

We had/have high water pressure, over 90 psi and we were replacing our pressure relief valve annually and the hot water tank on average every three to five years. I had a plumber install a pressure reducing valve and now the pressure is down to a more acceptable 60 psi.

MarkG

How would we check the pressure?

Steve_P

You'll need a plumber with a pressure meter.

Usually they just screw it onto the outside tap and turn it on full.

Bill_S

No it's not normal. But if the valve is not defective, it is doing its job: relieving excess pressure in the tank. As suggested above, get a plumber to examine your system to check the pressure. If the pressure is too high, you might need a pressure reducing valve, or an expansion tank. Indeed, you might have one of those and the problem lies there (valve not working properly, tank waterlogged). Get it checked soon. Small plumbing problems can quickly become big, expensive, and inconvenient plumbing problems.

MarkG

Yeah, we have an expansion tank near the water meter, but it's probably not been looked at since the house was built.

MarkG

Yeah, that's what the guy here said; since the instructions on the valve say to test it at least once a year by opening it, I guess the valve manufacturers want to ensure they have a thriving business in replacements .

Looks like I can get a water pressure gauge for a few dollars that screws onto a tap, so if it looks high I'll get the plumber to come in and do something about it.

Bill_S

DING DING DING DING DING! I'll bet that's where your problem is. The tank probably needs to be serviced or replaced. Try tapping on it from bottom to top, or side to side. If it sounds like it's completely full of water, it's kaput.

MarkG

Thanks, I'll give that a try!

MarkG

Yeah, I tried tapping the expansion tank and the sound at the top is the same as the sound at the bottom, so I suspect it's full. That would explain why the valve in the heater only leaks when I have a long shower, because there's probably enough space in the system to absorb the expansion of a smaller amount of cold water.

Guess we'll get the plumber in next week to check the whole thing out in case there are other problems we should fix. These Canadian houses sure are complicated compared to my parents' century-old place .

steve666

We're moving into a Canadian house on the 1st October, I had my own house sussed here in the UK quite quickly, heating, electric and water wise. The house we're going to has enough pipe work to function as a nuclear installation (and I've worked in one). It's going to be a joy to follow all the hollow metalwork to find out what goes where and why. I ask the relevant people over there if there is a schematic diagram of the electrical system and water systems running through the house and I got a negative answer. So I guess it's down to me and my son to sort the shit out.

Oh my god that sounded so MACHO!

Steve_P

When did they start putting in expansion tanks and where do they do this?

I don't think there are any such beasts in either of my boys homes here in Calgary and they are only five years old.

Certainly isn't anything in our house or the one we lived in before that.

Bill_S

Depends on how the house is connected to the municipal water supply. If the municipal pressure is high (over about 80 lb psi) then there will be a pressure-reducing valve installed in the house. These valves are one-way, so they create a "closed" system in the house. When the water heater causes the water in the tank to expand, you need an expansion tank to accomodate the extra volume. If there is no one-way valve in the system, the water can "expand" back into the municipal system.