Submitted by 18418871 t3_10of0p9 in DIY

Hot water tank seems to be malfunctioning. The water won’t get hot. When I turn it off and reset it, the flame burns orange and shuts off early before it reaches the desired temperature. Honeywell control unit is flashing five times for sensor failure. Any advice on what’s going wrong, how to fix and what can be done myself vs a plumber?

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wiffleplop t1_j6e6lcv wrote

Probably the thermocouple failing to tell the boiler that the gas is still lit. A new one is pretty cheap, but fitting it could be complicated. Have a look for how to guides.

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Sasparillakid t1_j6e7owc wrote

This sounds right. But a failing thermocouple is often the canary in the coal mine for a total tank failure.

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wiffleplop t1_j6e7wn2 wrote

I believe you. I’m in the UK, and we tend to have all-in-one boilers that supplies the radiators with hot water and the taps too. I wonder which is more efficient?

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South-Direct414 t1_j6fbebg wrote

I'd say as far as total energy consumption it's probably more efficient to separate the systems. That way you don't need to make your radiator out of human consumption rated materials, and you can also use more efficient heat transfer medium.

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celaconacr t1_j6fkknz wrote

I'm pretty sure condenser boilers are more efficient (94% for a new one). The radiators are on a separate loop not combined with the hot water system so you don't need human consumption rating.

Most modern houses in the UK use a "combi" boiler. That's a radiator loop heater and tankless hot water system in one. It heats the cold water feed direct for hot water on demand but that does mean a supply limit. Advantages are no efficiency loss through hot water storage, no space loss for the water tank, no legionnaires or similar concerns.

The other common type is a tanked system. Again the boiler does all the heating but in this case either feeding a hot water tank or the radiators. Hot water tanks are more common in older properties, those with pressure issues or those with too high demand for a direct feed.

We will probably be going back to tanks as we are slowly moving towards heat pumps from gas boilers.

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jet_heller t1_j6gc0in wrote

I doubt it. Generally, when they fail the burner won't even light.

My guess would be something with the exhaust. It's could well be clogged or something.

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Gh0stP1rate t1_j6id0yp wrote

Thermocouple failure would mean the burner doesn’t light at all. The main valve is shut until the pilot light heats up the thermocouple.

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Remem0 t1_j6foa1r wrote

Those Honeywell controllers are junk, and notorious for failing. They're also expensive.

If your water heater is under warranty, try to get a replacement for free, or at a steep discount.

I had three of them fail in five years on the same water heater. Pain in the butt.

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ObiDan71 t1_j6gets3 wrote

Too bad that Honeywell turned to garbage. I wonder where their parts are manufactured? 🤔

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MrPicklePop t1_j6fzjmf wrote

You can try to fix it or just scrap it and take advantage of the heat pump water heater tax credit if you’re in the US.

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18418871 OP t1_j6g82aa wrote

After some troubleshooting based on the feedback here, I think the issue might be the sensor; it currently has one of these:

https://www.homedepot.com/p/Rheem-PROTECH-Natural-Gas-Combination-Control-Thermostat-Replacement-Kit-SP21062A/311525399

When I relight the pilot after draining, cleaning and refilling, cleaning the gas bracket, it comes roaring for like 30 minutes with a blue flame but then stops (pilot still lit) once the water is lukewarm, leading me to suspect the water sensor is failing and mistakenly thinking the water is hotter than it really is.

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coolhandluke45 t1_j6gcvnx wrote

Try cleaning the flame sensing rod

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18418871 OP t1_j6gd2t5 wrote

Did that. And vacuumed the inside of the burn chamber, flame is now burning blue.

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booboo_bear t1_j6e9p1i wrote

Is the water heater still under warranty? The manufacturer sent me the parts. I hired a plumber to make sure they got installed properly

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A_Plumber2020 t1_j6fzip8 wrote

The valves are like the most expensive part of the heater. You can purchase them separately and they are fairly simple to install (if you are familiar with plumbing). Considering the age of the heater, you may be better off replacing the complete unit.

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deep-diver t1_j6g1ngi wrote

How many times did you try? Those things sometimes fit the definition of insanity… doing the same thing over and over, expecting different results.

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MIWHALKI t1_j6gdy2e wrote

we had that problem 2 days ago. It was our thermostat. A guy fixed it for us though.

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primak t1_j6gfqxk wrote

Replace the sensor. I had one where I had to repeatedly replace the sensor. It is a design flaw. The sensor is a tiny plastic part, but mine had cost about $20. It is very sensitive to dust, dirt, water, etc. and it will blow and tank won't work. You can google your model and find where the sensor is on it. Mine was under the temp control. Then remove it or get the part number online and google how to buy one.

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Gh0stP1rate t1_j6id3zg wrote

Orange flames and burner not staying on sounds like your intake air filter is clogged. Pull it out, vacuum it and vacuum everything under the water heater, and reinstall it all.

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booboo_bear t1_j6e9hns wrote

Is the water heater still under warranty. If so, the manufacturer could send the parts. I used a plumber to make sure the parts got installed properly.

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18418871 OP t1_j6e9t31 wrote

No it was installed in 2011, and came with the house purchase, I don’t think it’s still under warranty

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Hahadanglyparts t1_j6eabm3 wrote

10-12 years is about the lifetime of your average hot water heater. Could be time for a replacement.

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ledow t1_j6ffa9j wrote

If it's gas and you're in the UK it's literally illegal to tinker with it.

Don't.

Call a certified (Gas-safe) plumber.

You can't afford a £10m lawsuit if you damages your neighbour's house.

P.S. the flame should NEVER burn orange. It means it's burning incompletely and is a carbon monoxide risk.

Get a damn plumber.

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18418871 OP t1_j6fi1ar wrote

I’m in the US

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Signal-Ad8087 t1_j6g7417 wrote

Replace the thermocouple. when you do make sure electricity and gas to the system is off. It's cheap to try but will likely not buy you much time. When you do replace the coupler, drain the hot water tank. The will belp flush and crap out of it. Also clean stuff off and out as best you clean with a soft wire brush. It will cost you under 20.00 in most cases to try. Regardless if it works or not, prepare to replace it soon. I just replaced mine. It was 11 years old under same situation I bought an additional 2 years by doing this. Now ive upgraded to a 40 gallon . If you dont already have a 40 gallon, I don't recommend the upgrade if you have teens in the house. The more hot water available, the more they use it :/

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[deleted] t1_j6e81tb wrote

[deleted]

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grimlock99 t1_j6g31kf wrote

Scummy business practice right here that takes advantage of seniors and lazy people.

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ObiDan71 t1_j6g4x56 wrote

Not a senior and I can fix a water heater, just a convenience. In the past year, I have rebuilt the lawnmower engine, renovated all 3 bathrooms and removed the stucco and replaced it with tindle stone.

When there is no hot water, some if us want it resolved in the same day.

It is no different than having an apartment or condo and not being concerned with a bad roof or a broken window since it is part of the rental price or monthly condo fees.

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