KearnstdElf WizardPremium
join:2002-01-22
Mullica Hill, NJ | reply to monchis
Re: waterheater/gas - advice yep the blowoff safety is that pipe that is partly in the left side of your red box.
The reason it should have a pipe and that aims down to the floor is that its purpose is that in the event the thermostat on the WH fails and gets stuck in operational mode it will release the pressure of the tank in a safe manner. Well somewhat safe and that is what the pipe does, because when that baby does have to let go boiling water and steam will blast out of that valve. I do not know if such is code but it is more of a safety thing.
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 monchisPremium
join:2002-12-09
Los Angeles, CA
kudos:1 | said by Kearnstd:yep the blowoff safety is that pipe that is partly in the left side of your red box.
The reason it should have a pipe and that aims down to the floor is that its purpose is that in the event the thermostat on the WH fails and gets stuck in operational mode it will release the pressure of the tank in a safe manner. Well somewhat safe and that is what the pipe does, because when that baby does have to let go boiling water and steam will blast out of that valve. I do not know if such is code but it is more of a safety thing.
Makes total sense. Thanks for the heads up.
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 Jack_in_VAPremium
join:2007-11-26
Mathews, VA
kudos:1 | reply to Kearnstd
said by Kearnstd:yep the blowoff safety is that pipe that is partly in the left side of your red box.
The reason it should have a pipe and that aims down to the floor is that its purpose is that in the event the thermostat on the WH fails and gets stuck in operational mode it will release the pressure of the tank in a safe manner. Well somewhat safe and that is what the pipe does, because when that baby does have to let go boiling water and steam will blast out of that valve. I do not know if such is code but it is more of a safety thing.
Unless the house has a check valve in the cold water supply the water heater cannot build up pressure above the incoming water supply pressure. The pressure will equalize with that by forcing it into the cold supply. |
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robbinPremium,MVM
join:2000-09-21
Leander, TX
kudos:1 | said by Jack_in_VA:Unless the house has a check valve in the cold water supply the water heater cannot build up pressure above the incoming water supply pressure. The pressure will equalize with that by forcing it into the cold supply.
The house could have a pressure reducing valve and that would act as a check valve. But the point it that it is code for the relief valve to have a pipe on it so it can't blast someone if (when) it opens. Hopefully the plumber will pull a permit when replacing the old unit so this defect should be taken care of in the new install. |
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| reply to Jack_in_VA
said by Jack_in_VA:Unless the house has a check valve in the cold water supply the water heater cannot build up pressure above the incoming water supply pressure. The pressure will equalize with that by forcing it into the cold supply.
You shouldn't take everything so literally. Yes he did say "pressure" but he also said "thermostat ... gets stuck in operational mode." When that thing trips, be it due to over pressure or over temperature, very hot water under high pressure WILL come spraying out.
/M |
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Jack_in_VAPremium
join:2007-11-26
Mathews, VA
kudos:1 | reply to robbin
said by robbin:said by Jack_in_VA:Unless the house has a check valve in the cold water supply the water heater cannot build up pressure above the incoming water supply pressure. The pressure will equalize with that by forcing it into the cold supply.
The house could have a pressure reducing valve and that would act as a check valve. But the point it that it is code for the relief valve to have a pipe on it so it can't blast someone if (when) it opens. Hopefully the plumber will pull a permit when replacing the old unit so this defect should be taken care of in the new install. Pressure reducing valves PRV's can't act as a check valve. The construction is much different from what is required for a check valve. Most electric water heaters have an over-temp cut out switch high on the tank that is separate from the thermostats than can fail. It will cut the unit off long before the temp increases to the level to trip the T&P valve. I'm not sure about gas Water Heaters but I suspect they also have an OT to shut off the flame on over temp.
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 leiboldPremium,MVM
join:2002-07-09
Sunnyvale, CA
kudos:5
 ·SONIC.NET
| reply to Jack_in_VA
I hear more and more often from people having issues because their T&P valves are trickling water. In most cases this is due to the water utility replacing traditional water meters with a combination of water meter & backflow preventer with poor communication to the homeowner about the consequences of that change (specifically the need for an expansion tank).
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robbinPremium,MVM
join:2000-09-21
Leander, TX
kudos:1 | reply to Jack_in_VA
said by Jack_in_VA:Pressure reducing valves PRV's can't act as a check valve. The construction is much different from what is required for a check valve.
they are treated the same in other parts of code. From your neck of the woods --
"Water Heaters and Expansion Tanks
The need for an expansion tank with new or existing water heaters has been a point of confusion for many. The information below will hopefully provide clarity on this issue for plumbers and homeowners alike.
Where Required
Expansion tanks are required when a plumbing system contains a check valve, backflow preventer, pressure reducing valve or a pressure increasing pump. Most homes in Fairfax County, the town of Vienna and the city of Falls Church do not require any of these devices, and therefore, an expansion tank is not required."
»www.fairfaxcounty.gov/dpwes/cons···ters.htm |
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Jack_in_VAPremium
join:2007-11-26
Mathews, VA
kudos:1
1 edit | reply to leibold
said by leibold:I hear more and more often from people having issues because their T&P valves are trickling water. In most cases this is due to the water utility replacing traditional water meters with a combination of water meter & backflow preventer with poor communication to the homeowner about the consequences of that change (specifically the need for an expansion tank).
Then the utility would be liable if they fail to inform the homeowner of the change and what would be needed to make it safe. An expansion tank is essential if a check valve is on the supply. Most likely thought if that amount of pressure built up a hose on the clothes washer or fridge ice-maker would let go.
T&P valves typically are set at 150 psi and 210 F. On gas water heaters there is a gas shutoff valve that is independent of other controls that shuts the gas off at 210 degrees F.
I don't have a water meter or check valve so it doesn't apply to me.
Besides the original topic was the improper venting causing the gas company to not leave the pilot on. The Land-Lord is replacing the Water Heater so the problem should be solved. |
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robbinPremium,MVM
join:2000-09-21
Leander, TX
kudos:1 | said by Jack_in_VA:I don't have a water meter or check valve so it doesn't apply to me.
This thread isn't about you. It's about a person apparently renting in California. Don't you think they should have the information to make their own decision as to if it applies to them as well as to their risk if the relief valve opens while they are standing there. |
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Jack_in_VAPremium
join:2007-11-26
Mathews, VA
kudos:1 | said by robbin:said by Jack_in_VA:I don't have a water meter or check valve so it doesn't apply to me.
This thread isn't about you. It's about a person apparently renting in California. Don't you think they should have the information to make their own decision as to if it applies to them as well as to their risk if the relief valve opens while they are standing there. As stated by the OP the WH T&P can not operate because the gas company will not supply gas to the burner. Therefore no heat or pressure. The OP also stated the WH was going to be replaced by the Land-Lord. Problem should be solved as the old unit is essentially moot. Assuming the new WH should be installed per existing codes there is no problem. |
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robbinPremium,MVM
join:2000-09-21
Leander, TX
kudos:1 | Once again, isn't it a good idea to give the OP information so they can be aware of potential problems. Personally I don't care if the plumber pulls a permit, just that they did the job as if they did. The permit issue is between the OP and their landlord as far as I'm concerned. But when the OP posts a pic of the new water heater I'm sure that many here will review the install for occupant safety and code compliance. |
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