I have a low pressure hot water system that has a Nefa pressure relief valve instead of a vent pipe. This has been leaking which has given me a horrific power bill, like having a permanent dribbling hot tap. Should I replace it, or are repair kits available? or is there a better valve available these days? The pressure reducing valve isnt over pressuring the system, and the cylinder isnt boiling the water off.
tegretol,
Apr 23, 1:20pm
Replace it - they are not that dear (I think about $50). If your water source is an Apex valve, I'd fit two PRV's just in case. It it's only a header tank then one is plenty as pressure can't really ever get high enough to blow the tank.
Replacing a valve washer on a Nefa valve is a relatively simple process that can be done with a few basic tools. Here are the steps to follow:
Turn off the water supply: Before beginning any work on the valve, it is important to turn off the water supply to the area. You can usually find a shut-off valve located near the plumbing fixtures or main water supply line.
Remove the handle: Use a screwdriver to remove the screw located in the center of the handle. Once the screw is removed, pull the handle off the valve stem.
Remove the packing nut: Using an adjustable wrench, loosen and remove the packing nut that is located just beneath the handle.
Remove the valve stem: Carefully pull the valve stem out of the valve body. You may need to use pliers to grip the stem and pull it out.
Replace the washer: On the end of the valve stem, you should see the old washer. Remove it and replace it with a new one. Make sure the new washer is the correct size and shape for your valve.
Reassemble the valve: Carefully reinsert the valve stem into the valve body. Replace the packing nut and tighten it with your wrench. Reattach the handle and screw it back into place.
Turn on the water supply: Once everything is reassembled, turn the water supply back on and test the valve to ensure it is working properly.
That's it! With these simple steps, you should be able to replace a valve washer on a Nefa valve.
budgel,
Apr 23, 2:51pm
I'm not worried about the price, just wondered if they were a bit old tech and there might be something newer/better. What does two pressure reducing valves achieve?
shakespeare6,
Apr 23, 3:00pm
I have the pressure relief valve on the top then just above my Ajax valve between that and the bottom of the cylinder I have a cold water expansion valve. So when my waters heating and expanding my cold water expansion valve releases the pressure as this is set lower than the PRV. That way you are only ever expanding off cold not hot. Saves a couple bob I guess
tegretol,
Apr 23, 3:12pm
An extra degree of safety. If the ajax fails and the PRV doesn't release, you have a bomb on your hands. Fit two and reduce the risk of that happening.
trade4us2,
Apr 23, 5:07pm
There are repair kits. I found that the spring goes rusty and collapses. https://trademe.tmcdn.co.nz/photoserver/full/775849585.jpg You could just buy a new spring every 5 years. But I threw the valve out and put the copper overflow pipe back up to the roof. I put a 2 litre tank on top of the pipe, and it never overflows now.
lythande1,
Apr 24, 3:55am
In low pressure systems you have both. Check the washer first, sometimes it's just that. If that doesn't cure it, then replace it.
elect70,
Apr 24, 6:52am
Take it apart , clean the diapham /washer , any bit of dirt can allow it to leak . I did this with mine & Ok now
johotech,
Apr 29, 6:07am
x1
There must be something about your water. Or it's because it's installed horizontally.
Here's a photo of one that's over 10 years old. Virtually no rust. It was letting water through, but it was just dirty.
It doesn't matter which way the valve is oriented, the water has to run over the spring. The spring is just zinc plated steel, and goes rusty after a few years. Do you agree that the water runs over the spring every time the hot water is used? Do you agree that the spring is not stainless steel?
johotech,
Apr 29, 12:43pm
You can see the tide mark on your spring where the water is constantly sitting in water, because parts of the spring are lower than the drain hole when it's horizontal. When it's installed vertical, I think the water can drain away.
It's not stainless I guess. I didn't check. Yes some water comes out the relief when cold water is heated and there's expansion. Not whenever you run the tap though.
I just posted the photo because this valve is more than 10 years old, and there's no significant rust like the springs you always post photos of.
So what you claim every time there's a post about hot water systems, that these valves only last 5 years, isn't actually true in all cases.
trade4us2,
Apr 29, 2:11pm
That is just one of the four springs that have gone rusty. If it's installed vertical, the hot water still runs over the spring several times a day. Anyway, the whole idea of these valves is stupid. They waste hot water every day. There are better ways of handling the expansion.
budgel,
Apr 30, 3:47am
Such as?
trade4us2,
Apr 30, 4:08am
The easiest way to handle water expansion is a simple overflow pipe to 7.6 metres above the bottom of the cylinder (if that is the pressure rating for the cylinder). I have seen a pressure release valve that releases cold water instead of hot. However that can fail also, and most plumbers don't put the overflow pipe where it can be checked easily for overflowing. If my pipe overflows it makes a loud noise on the roof. Since I have a 2 litre tank on top, it is extremely unlikely to overflow.
mrcat1,
Apr 30, 11:04am
It will be the small seal in the ajax valve that is leaking, about the size of a finger nail, take the cap off and push out the brass bar and it will come out in a little holder, pries it out carefully and install a new one and O ring around the cap and it will be sorted.
trade4us2,
Apr 30, 11:24am
No, with my Nefa valve the spring goes rusty and collapses.
supernova2,
Apr 30, 8:07pm
x1
But isn't the spring on the dry side of the diaphragm?
trade4us2,
May 1, 12:37pm
This is a pressure relief valve at the top of the cylinder that releases water when cold water heats up. That water runs over the spring. The pressure reducing valve under the cylinder can last for many years until the diaphragm perishes. That spring stays dry.
johotech,
May 1, 1:10pm
Yes it is. And if they are installed vertically, the water runs through the white pipe that's inside the spring, and drains freely instead of the spring constantly sitting in water - evidenced by the tide mark on Mr. trade4us photo.
And about a $4 cost, I always keep a spare taped to the door, for when I hear that dribble on the roof
trade4us2,
May 3, 3:59pm
The tide mark was on the first valve installed horizontally by a plumber. I then put the valve vertical with a new spring, and that one went rusty and collapsed. And so did the next one. This is the last spring that was installed vertically https://trademe.tmcdn.co.nz/photoserver/full/783076394.jpg So OK it takes a few years for the spring to rust, but eventually it collapses and wastes about $50 of power and water before I notice the leak. The valves are unsuitable for the purpose for which they are sold.
oddbits,
May 3, 4:34pm
x1
replace it better in the long run and they are inexpensive if you do it yourself
budgel,
May 5, 9:09am
I ended up doing just that. All good now.
trade4us2,
May 5, 9:36am
Why not open up the valve and see what is wrong with it?
budgel,
May 7, 5:41am
I did, and the plastic tube had cracked.
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