Hot water cylinder overflow detector , alarm

Forums › Home Workshop DIY › Hot water cylinder overflow detector , alarm

1 | 2

mdooher

Hmm, what to write...
1444 posts

Uber Geek
+1 received by user: 910

ID Verified

Trusted

Lifetime subscriber

#2663094 26-Feb-2021 12:07

Lets start again. you say it is a vertical pipe? this is normally the HW overflow

was hot water or cold water coming out? if hot then this is again the HW overflow but it would not have been fixed by a washer replacement

if it was horizontal and cold water coming out then it is the header tank overflow. which might have been fixed with a washer. (it works the same way a toilet works)

Matthew

lyhnz

11 posts

Geek

#2663095 26-Feb-2021 12:09

Thanks actually what you said is the cheap option I want, ok, my low pressure relief valve, what elbow, where to buy, size , specs, what pipe , size, material? thank you very much .

DonH

232 posts

Master Geek
+1 received by user: 158

Lifetime subscriber

#2663096 26-Feb-2021 12:12

mdooher:

You put a pressure relief valve on a Low pressure cylinder overflow? ... how would that increase the pressure? it would just blow back into the header tank.

There are two types of low pressure system. One type has a header tank somewhere above the cylinder. As you draw hot water, cold water flows down from the header tank to replace it. The level in the header tank drops, opening a ballcock (same as in a toilet cistern) to refill the header.

The other type has no header tank. Instead, the cylinder gets refilled directly from the mains via a pressure reducing valve. ("Ajax" valve). There is a long pipe extending above the cylinder, usually sticking out of the roof. Once the cylinder is full, the water rises up the pipe. This increases the back pressure on the valve, closing it. Drawing off hot water lowers the water level and thus the pressure, opening the valve. If the valve is maladjusted / leaky, the water overflows at the top of the pipe.

With both systems, if the cylinder is filled with cold water and then heated, the water expands. In a header system, the water expands up into the header tank, usually unnoticed because the header is not full to the brim. With the "Ajax" system, the water expands up the pipe and can drip from the top.

Putting a pressure valve on top of the "Ajax" pipe (and increasing the Ajax valve setting) will raise the pressure in the system. You have to be careful not to exceed the cylinder pressure rating of course.

For the OP's issue, a right-angle elbow on the top of the Ajax pipe will make overflow easier to see. Since it's likely a standard copper pipe, a simple copper elbow slipped over the end of the pipe should do. See your local plumber's merchant...

People hear what they see. - Doris Day

wellygary

8830 posts

Uber Geek
+1 received by user: 5312

#2663098 26-Feb-2021 12:15

lyhnz:

Matthews, as you said every 6 mth to check it , I have the risk if it overflows 4 mth without notice

Your power bill will tell you something is wrong well before 6 months...

lyhnz

11 posts

Geek

#2663099 26-Feb-2021 12:28

wellygary:

lyhnz:

Matthews, as you said every 6 mth to check it , I have the risk if it overflows 4 mth without notice

Your power bill will tell you something is wrong well before 6 months...

That is why I want to know any early prevention for this , to know it happens then quickly change the the ajax washer as per my previous experience

lyhnz

11 posts

Geek

#2663101 26-Feb-2021 12:31

DonH:

mdooher:

You put a pressure relief valve on a Low pressure cylinder overflow? ... how would that increase the pressure? it would just blow back into the header tank.

There are two types of low pressure system. One type has a header tank somewhere above the cylinder. As you draw hot water, cold water flows down from the header tank to replace it. The level in the header tank drops, opening a ballcock (same as in a toilet cistern) to refill the header.

The other type has no header tank. Instead, the cylinder gets refilled directly from the mains via a pressure reducing valve. ("Ajax" valve). There is a long pipe extending above the cylinder, usually sticking out of the roof. Once the cylinder is full, the water rises up the pipe. This increases the back pressure on the valve, closing it. Drawing off hot water lowers the water level and thus the pressure, opening the valve. If the valve is maladjusted / leaky, the water overflows at the top of the pipe.

With both systems, if the cylinder is filled with cold water and then heated, the water expands. In a header system, the water expands up into the header tank, usually unnoticed because the header is not full to the brim. With the "Ajax" system, the water expands up the pipe and can drip from the top.

Putting a pressure valve on top of the "Ajax" pipe (and increasing the Ajax valve setting) will raise the pressure in the system. You have to be careful not to exceed the cylinder pressure rating of course.

For the OP's issue, a right-angle elbow on the top of the Ajax pipe will make overflow easier to see. Since it's likely a standard copper pipe, a simple copper elbow slipped over the end of the pipe should do. See your local plumber's merchant...

Thanks you understand what I mean correctly, an extension pipe letting me notice it. do you have idea the pipe diameter? my one is ajax standard vertical pipe. also adding an elbow to change the direction I hope not add pressure on the pipe resulting in water flow not smoothly.

Lego

Shop now for Lego sets and other gifts (affiliate link).

Dynamic

4020 posts

Uber Geek
+1 received by user: 1857

ID Verified

Trusted

Lifetime subscriber

#2663113 26-Feb-2021 13:37

@lyhnz, can you see the top of the hot water overflow pipe that is probably sticking out the top of your roof? If yes, ask a local plumbing merchant for something you can screw to the top of this vertical pipe to add a 90 degree angle to it, and a short length of pipe to poke out of it so you can better see drips or trickles of water. Copper water pipe is a standard size, so they will know what you need.

If you cannot see the pipe, I guess the same 90 degree angle joiner plus some flexible water pipe so you can direct the water to an area of the roof you can see? You should be able to see the section of the roof is slightly wet if a leak develops. Or have the end of the hose off the edge so you can see drips on the concrete.

“Don't believe anything you read on the net. Except this. Well, including this, I suppose.” Douglas Adams

lyhnz

11 posts

Geek

#2663116 26-Feb-2021 13:53

Dynamic:
@lyhnz, can you see the top of the hot water overflow pipe that is probably sticking out the top of your roof? If yes, ask a local plumbing merchant for something you can screw to the top of this vertical pipe to add a 90 degree angle to it, and a short length of pipe to poke out of it so you can better see drips or trickles of water. Copper water pipe is a standard size, so they will know what you need.

If you cannot see the pipe, I guess the same 90 degree angle joiner plus some flexible water pipe so you can direct the water to an area of the roof you can see? You should be able to see the section of the roof is slightly wet if a leak develops. Or have the end of the hose off the edge so you can see drips on the concrete.

Thanks,will do,that is all I want to know.cheers. my one is vertical and can see from the roof top, you guys are awesome

DonH

232 posts

Master Geek
+1 received by user: 158

Lifetime subscriber

#2663147 26-Feb-2021 14:57

I've seen advice here to attach a pipe or hose to bring the water down to somewhere visible. If anyone does this, remember to drill a small hole on the very top where it joins the vertical pipe. Otherwise the first time it overflows it will form a syphon and drain all your hot water... 😀

As for the elbow solution, there are a couple of common copper water pipe sizes so you could measure it to be on the safe side. If you can access it inside the ceiling to measure it this would be safer than climbing on the roof. The cheapest option will be the type of elbow that simply slips over the end of the pipe. It is designed to be soldered on but since there is no pressure it won't come off. There are also elbows with a locking ring like a garden hose fitting. Get brass, not plastic, it will withstand heat and UV.

People hear what they see. - Doris Day

lyhnz

11 posts

Geek

#2663163 26-Feb-2021 15:29

DonH:

I've seen advice here to attach a pipe or hose to bring the water down to somewhere visible. If anyone does this, remember to drill a small hole on the very top where it joins the vertical pipe. Otherwise the first time it overflows it will form a syphon and drain all your hot water... 😀

As for the elbow solution, there are a couple of common copper water pipe sizes so you could measure it to be on the safe side. If you can access it inside the ceiling to measure it this would be safer than climbing on the roof. The cheapest option will be the type of elbow that simply slips over the end of the pipe. It is designed to be soldered on but since there is no pressure it won't come off. There are also elbows with a locking ring like a garden hose fitting. Get brass, not plastic, it will withstand heat and UV.

You are simply fantastic , by the way are you a plumber? Auckland? I would like to ask you do the job next time if any plumbing job.

DonH

232 posts

Master Geek
+1 received by user: 158

Lifetime subscriber

#2663166 26-Feb-2021 15:44

lyhnz:

You are simply fantastic , by the way are you a plumber? Auckland? I would like to ask you do the job next time if any plumbing job.

You're welcome. 😀 No, I'm just mechanically minded. I know just enough to be a danger to myself and others.

People hear what they see. - Doris Day

1 | 2