Forums > Specific Focus > Home, Garden & Construction in Mexico

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stevebrtx

Jan 3, 2012, 6:24 AM

Post #1 of 33 (7452 views)

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Maybe for water hammer?

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I notice on the roof of many houses the supply pipes have been extended up a foot or two, why? Is it to prevent water hammer? They're totally remodeling the multi unit complex next to me and put in all new plumbing and left stubs of both hot and cold supply sticking up and capped on each unit.
http://www.chapalaweather.net

DavidHF

Jan 3, 2012, 7:17 AM

Post #2 of 33 (7438 views)

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Re: [stevebrtx] Maybe for water hammer?

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My roof had stubs of hot and cold, they came in handy when installing the solar water heater. No long plumbing runs needed!

joaquinx

Jan 3, 2012, 7:55 AM

Post #3 of 33 (7426 views)

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Re: [stevebrtx] Maybe for water hammer?

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If I read you correctly, these pipes are vents for the water heater. Most heaters do no have a thermostat, but a gas cut-off (if the flame is blown out, the cut-off will turn off the gas). If the gas isn't manually turned off and the water boils, the steam and hot water can escape up the vents
_______
My desire to be well-informed is currently at odds with my desire to remain sane.

morgaine7

Jan 3, 2012, 7:59 AM

Post #4 of 33 (7422 views)

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Re: [stevebrtx] Maybe for water hammer?

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My house has those pipe extensions, with valves on them, and the plumbing contractor told me it's so that in case the power or pressure pump fails, I can open the valves and get better gravity feed from the roof tank. That's what I understood, anyhow.

Kate

Rolly / Moderator

Jan 3, 2012, 9:03 AM

Post #5 of 33 (7417 views)

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Re: [joaquinx] Maybe for water hammer?

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Most heaters do no have a thermostat
That is a pretty big overstatement.

Rolly Pirate

joaquinx

Jan 3, 2012, 9:13 AM

Post #6 of 33 (7413 views)

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Re: [Rolly] Maybe for water hammer?

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In Reply To

Most heaters do no have a thermostat
That is a pretty big overstatement.

Perhaps not in your neighborhood, but to folks on the low end of the pay scale, their hot water heaters do not have thermostat. A question of the percentage is debatable. Mine doesn't and neither do my neighbors. In all the apartments that I have rented, they didn't.
_______
My desire to be well-informed is currently at odds with my desire to remain sane.

chicois8

Jan 3, 2012, 9:44 AM

Post #7 of 33 (7401 views)

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Re: [stevebrtx] Maybe for water hammer?

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since you say both are capped they could be a water / air hammer or just a place to connect when a possible second story is built called futures......it is a pressure system,correct?

(This post was edited by chicois8 on Jan 3, 2012, 9:46 AM)

stevebrtx

Jan 3, 2012, 9:46 AM

Post #8 of 33 (7398 views)

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Re: [joaquinx] Maybe for water hammer?

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What MXN heaters do NOT seem to have is an emergency popoff. A few months ago the maintenance guy was tinkering with the thermostat and it stuck. A couple hours later I went to water my plants and I boiled a bougainvillea before I realized the water was so hot it had backed up in the incoming cold water side. I immediately ran to the propane tank and cut it off and started opening faucets to bleed off pressure, the steam literally melted a plastic shower head. It was only a miracle I happened to water that plants at that time of day otherwise it would have blown the end off the house.

The heater was put in two years ago and it thumps and bumps and has since day one, as does the one on the casita, I have no idea why. MXN plumbing remains a mystery to me, no vent stack on the waste side, but stubs on the supply?
http://www.chapalaweather.net

chicois8

Jan 3, 2012, 9:51 AM

Post #9 of 33 (7396 views)

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Re: [joaquinx] Maybe for water hammer?

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How can they be vents if they are capped and hot water heaters should be equipped with a T&P Valve which stand for temperature & pressure relief valve, when either the temp gets too high or pressure gets too high it relives itself...

(This post was edited by chicois8 on Jan 3, 2012, 9:54 AM)

joaquinx

Jan 3, 2012, 10:04 AM

Post #10 of 33 (7392 views)

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Re: [chicois8] Maybe for water hammer?

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I have two vertical pipes leading from the top of my heater. When the water temperature hits 100C, plumes of hot water and steam will come spurting out the top of these pipes. My neighbors have them and practically every house that I see, has them. I suppose that in the wealthier neighborhoods, houses would be equipped with hot water heaters that have thermostats and T&P valves.

I have seen plumes of hot water geysers shooting 15+ feet out of these vents.

I really doubt that Mexican house have enough water pressure to need compression pipes for water hammer. I remember my father installing them in his house. Of course his water pressure was 45 psi!!
_______
My desire to be well-informed is currently at odds with my desire to remain sane.

(This post was edited by joaquinx on Jan 3, 2012, 10:06 AM)

stevebrtx

Jan 3, 2012, 10:33 AM

Post #11 of 33 (7379 views)

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Re: [joaquinx] Maybe for water hammer?

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I can assure you mine are hard capped with NO popoff valves and neither are the new installations next door. My pressure pump is set at about 45psi, but my pressure in TX was more like 75-80, so this is a dribble by comparison. Now, to be fair, the hot stem might be a great place for a popoff, and I'll check into doing that, after my brush with disaster I'm a bit spooked. The other morning I woke a bit early and heard the heater bubbling? - not bumping and thumping as usual and I wondered why, a bit later when I got up I found out why, no agua at all, the gardener had pumped the aljibe dry the night before watering everything and the pressure pump had been on all night long blowing bubbles in the heater which also cost me 7KWH in juice.
http://www.chapalaweather.net

chicois8

Jan 3, 2012, 10:38 AM

Post #12 of 33 (7377 views)

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Re: [joaquinx] Maybe for water hammer?

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The OP says they are capped, there not vents if they are capped, that is why I mentioned if it maybe a pressure system...

You know better, why don't you have a T&P Valve in your hot water heater?

sparks

Jan 3, 2012, 2:13 PM

Post #13 of 33 (7348 views)

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Re: [stevebrtx] Maybe for water hammer?

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I have two that are capped from my original plumber and my current plumber says they should have pressure relief valves or air release valves. I assume something other than a pressure relief valve for a water heater because the pressure is less.

Hot water pressure release can be just above the tank.

Thermostat is what turns the gas off and on ... otherwise it would be on all the time.

Sparks Mexico - Sparks Costalegre

chicois8

Jan 3, 2012, 3:25 PM

Post #14 of 33 (7334 views)

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Re: [sparks] Maybe for water hammer?

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I have two that are capped from my original plumber and my current plumber says they should have pressure relief valves or air release valves. I assume something other than a pressure relief valve for a water heater because the pressure is less.

So did you have you plumber install the air vents for you like he recommended?

Hot water pressure release can be just above the tank.

Many new tanks have a 3/4" threaded outlet on the side of the tank for easy installation...

Thermostat is what turns the gas off and on ... otherwise it would be on all the time.

Or off.........

whynotwrite

Jan 4, 2012, 8:49 AM

Post #15 of 33 (7294 views)

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Re: [sparks] Maybe for water hammer?

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"I assume something other than a pressure relief valve for a water heater because the pressure is less. " So water that is heated (and has expanded) in a water heater tank is under less pressure than what??

sparks

Jan 4, 2012, 1:44 PM

Post #16 of 33 (7270 views)

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Re: [whynotwrite] Maybe for water hammer?

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Less pressure than street or tinaco

Sparks Mexico - Sparks Costalegre

cbviajero

Jan 4, 2012, 1:58 PM

Post #17 of 33 (7265 views)

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Re: [whynotwrite] Maybe for water hammer?

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No T&P valve,no earthquake straps and no insulation blankets thats how I've seen water heaters installed here.IMO most of the plumbers and electricians here are not up to speed, that said there are a lot of very good masons and carpenters.Having spent 35 years working in residencial construction I'm seriously unimpressed with the mechanical systems installed in most of the homes here.
Chris

DavidHF

Jan 4, 2012, 2:31 PM

Post #18 of 33 (7260 views)

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Re: [cbviajero] Maybe for water hammer?

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We live in a house built in 1989 and the water heater has a pressure relief valve.

cbviajero

Jan 4, 2012, 3:13 PM

Post #19 of 33 (7251 views)

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Re: [DavidHF] Maybe for water hammer?

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That's good,some straps to anchor it in case of temblors and an insulation blanket depending on your climate zone and your set.
Chris

DavidHF

Jan 4, 2012, 3:52 PM

Post #20 of 33 (7246 views)

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Re: [cbviajero] Maybe for water hammer?

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It's only 2 ft. tall, has a 10 liter tank and is turned off since it's only the backup for the solar heater.

stevebrtx

Jan 4, 2012, 5:56 PM

Post #21 of 33 (7233 views)

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Re: [DavidHF] Maybe for water hammer?

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I brought down insulation blankets for both here and made a sizable difference, guess I'll have to poke around and see if I can find a couple of popoff valves.
http://www.chapalaweather.net

Papirex

Feb 9, 2012, 10:51 AM

Post #22 of 33 (6848 views)

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Re: [joaquinx] Maybe for water hammer?

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All water heaters built in the past few decades have a thermostat. It does not require any external power to operate. A device called a thermopile supplies the tiny amount of electricity to operate the thermostat.

The thermopile is in the flame of the pilot light. The heat causes a few molecules from one pole of the thermopile to jump to the other pole, generating a tiny amount of electricity. It is a tiny amount, measured in micro-volts. It is enough to operate the thermostat though. As long as you have gas, and a pilot light flame the thermostat will function. Many self contained wall heaters, etc. use the same technology, no external power is required.

As to the external piping vents, they are completely unnecessary If the “Plumber” or homeowner knows enough to open some valves in the house when filling, or recharging the water system to let the air escape. When all of the valves stop blowing the air out, and begin to deliver water, The system is fully charged, and functional.

The only advantage to using the piping vents is that they eliminate the need for a relief valve for the water heaters here. If the thermostat is stuck in the open, or burn position, The water in the tank will exceed the boiling point. The hot water heater tank will finally fracture, and the water in it will immediately flash into steam, with deadly, explosive force.

They are at least a century behind in technology down here, I guess that is to be expected in a country that has no effective building or licensing codes, they are a necessary evil.

Rex
"The supreme happiness of life is the conviction that we are loved" - Victor Hugo

YucaLandia

Feb 9, 2012, 12:07 PM

Post #23 of 33 (6836 views)

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Re: [Papirex] Maybe for water hammer?

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Hey Papirex,
The thermopile design looks interesting. How well do they work?
Do they do OK for years in exterior Tropical installations?
What power does the circuitry connected to the little thermocouples need to work? (Most of our installs here in Yucatan do not have electricity near the water heaters.)

We don't have anything like this in our plumbing and hardware stores, so this stuff has me curious. Merida is a city of roughly million people, but we don't have these. Instead, our water heaters use an old-school "thermocouple" where a copper bulb sits in the pilot light flame - controlling the valve that allows gas to flow to the burner - no circuitry - nothing fun like a thermopile.
steve
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Read-on MacDuff
E-visit at http://yucalandia.com

(This post was edited by YucaLandia on Feb 9, 2012, 1:10 PM)

Rolly / Moderator

Feb 9, 2012, 12:17 PM

Post #24 of 33 (6830 views)

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Re: [Papirex] Maybe for water hammer?

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Here is a very informative article on T&P Valves.

Rolly Pirate

RickS

Feb 10, 2012, 7:40 AM

Post #25 of 33 (6785 views)

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Re: [Rolly] Maybe for water hammer?

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Now that was comprehensive!

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