water heater question

Hello world,

I’m currently choosing a water heater, and the tankless models look the best for me, as I don’t have much space to install a unit.
I’ve already read this [article](https://www.finehomebuilding.com/2019/08/30/tankless-water-heaters-2) and [this one](https://houseweather.org/best-gas-tankless-water-heater/)

Still, can’t decide whether I’m going for gas or electric heater…
So, you’d be very helpful if write some pros and cons

thanks a lot

Guest User | 4 years and 7 months ago

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hkapstein | 4 years and 2 months ago

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I’d personally try to figure out what the problem is before I hired a plumber(and then I would hire a plumber to fix it). You’ll be paying 200-300 bucks an hour, and it’s very unlikely you’ll get a master plumber at your site. Paying someone to troubleshoot a vague problem can get expensive fast. Master Plvmer is a good plumber and wouldn’t rip you off, at least that’s my impression. But my experience with NYC plumbers has not been a great one. I can easily imagine spending 500-1000 bucks, and not getting the problem resolved, or getting upsold something crazy.

If the plumber shows up, it would be great if you could say, “Here’s what happened, I think it needs a new expansion tank”, then they can check it, and are much less likely to take you for a ride if it seems like you actually know what is going on.

Now there’s some stuff you should know about your setup. You don’t necessarily want to mess with your water heater temperature for convenience. Storing the water at too low a temperature can create a legionella hazard, but too high can create a scald hazard at the fixtures. Usually a mixing valve is used so the water can be stored above 140 and delivered around 120. I’d have your plumber explain how this is set up, and whether it’s working properly, or if you might want to add a mixing valve if one isn’t present.

JohnHancock | 4 years and 2 months ago

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I would listen to Master Plumber’s advice, he’s a pro who does this for a living and runs a solid business

hkapstein | 4 years and 2 months ago

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Here’s some starting points to think about.

Why is there an expansion tank if there’s no backflow device? It’s possible it’s a redundant, but that would be odd. A plumber would normally notice an expansion tank going in when it isn’t needed.

Now suppose there is no backflow device. Is it possible that a manual valve was closed with the leak occured? If the water service was shut off and the tank fired, that does seem like a situation that could open the valve, possibility, and most likely if the expansion tank wasn’t working. Are you sure the expansion tank is not part of your heating system?

Can you post pictures of your setup?

Master Plvmber | 4 years and 2 months ago

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You need a professional to look at this. If the expansion tank is old and ruptured internally then it’s not doing its job, even though it may look fine from the outside.
It takes a lot to activate a water heater relief valve. There are different models for commercial equipment, but overwhelmingly the ones we use in our homes open to release water at 150 PSI or 210°F so whatever set yours off, and then self-corrected to allow the valve to close, is a condition you don’t want have happen again.

To give this some perspective, the water pressure in NYC residential buildings without roof tanks or pressure booster systems is generally measured at around 45-55 PSI. Residential water heaters set at their highest setting generally create 140°F water maximum. So, a water heater relief valve is not a sensitive device. It’s there to activate in an emergency. You had one of those emergencies.

Guest User | 4 years and 2 months ago

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Thank you so much. Sorry it’s taken so long to respond.

I’m not sure what temperature the heater is set to. The options are Vacation, Low, Hot, A, B, C, and Very Hot in that order. Ours is set to Hot, although the water coming out of the faucet is often too hot, but if we put it closer to Low, the water ends up being too cold.

I don’t believe there’s a backflow preventer or a check valve on the water line. We do, however, have an expansion tank, but that might have been accidentally left in the plans from a previous version of our plans that did call for a backflow preventer, so one was installed but from the sounds of things might not have been necessary?

If there’s no backflow preventer or check valve, but there is an expansion tank, can excess pressure still build up?

Could the high temperature have something to do with this? From the water coming out of the faucet, you’d think we had the heater set on the highest setting, but we don’t.

hkapstein | 4 years and 2 months ago

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The pressure in the system has exceed the valve spec or the valve is bad. If there is no backflow preventer or check valve, excess pressure can push back into the water service line, that is why eman137 twice asked about this. If there is a backflow prevention device, then expansion in the system could force water out the valve when heated and the expansion tank should be checked and it’s job is to compensate for this effect.

Guest User | 4 years and 2 months ago

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what is the temperature of the heater set at? is there a check valve on the cold water supply?

Guest User | 4 years and 2 months ago

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Thank you! It’s no longer dripping. Does that mean it’s okay or should we still have it looked at?

Guest User | 4 years and 2 months ago

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it is either a failing T&P valve, or if you have a check valve on the water heater, a lack of or failed domestic water expansion tank

lkrshacmzcy | 4 years and 7 months ago

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^ Tankless Units are not designed with a Space Saving purpose; they are designed to be High Efficient Units.

lkrshacmzcy | 4 years and 7 months ago

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^ Tankless Units are not designed with a Space Saving purpose; they are designed to be High Efficient Units.

Master Plvmber | 4 years and 7 months ago

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You probably don’t have enough power for an adequate electric one and chances are pretty good you don’t have a compliant way to vent a gas one.