Where did all my hot water go?

[Augusto Orosco]

Fellow Creekers,

I am having the pros coming over on Monday, but I thought of picking the collective brain here, so I can have an informed conversation when they come.

My house heat is provided by an oil furnace that heats water and pumps it through the baseboard heaters. The same furnace takes care of the hot water (it’s a tank-less system). Here’s my problem: I don’t get hot water anymore. At best, I get warm water, not steaming hot anymore (shaving hasn’t been fun lately! :mad:). This just started a few days ago, just as the furnace load got drastically reduced with the higher temperatures (coincidence?).

The furnace seems to be working fine. It keeps the internal tempereature between 180 and 200 degrees and the system is at about 15psi, as required by the manual. I have turned the mixing valve from 120 to 160, but it hasn’t made much of a difference.


Any ideas?

[Tim Morton]

220v heater? Maybe you lost a leg and its running on 110 now?

[Augusto Orosco]

220v heater? Maybe you lost a leg and its running on 110 now?

I just went down to the basement and checked, Tim. The burner runs on 120v with a dedicated 15amp circuit.

[Josh Davis]

Maybe my wife has been using all your hot water too?

[Joe Pelonio]

Maybe my wife has been using all your hot water too?
Good one!

Does the water flow to through the heating via just the existing water pressure, or might there be a circulating pump for it (which has died)?

[Augusto Orosco]

Does the water flow to through the heating via just the existing water pressure, or might there be a circulating pump for it (which has died)?

No pump, Joe... just the existing water pressure. If it helps, the baseboards still get the necessary hot water to keep the water warm at night (the only time now when temp drop is big enough)

[Frank Hagan]

Usually you can get 4 to 5 gpm out of the heat exchanger coils attached to an oil boiler; you could have a problem with the coil itself or the distribution (a circulator or diverter valve).

[Augusto Orosco]

Usually you can get 4 to 5 gpm out of the heat exchanger coils attached to an oil boiler; you could have a problem with the coil itself or the distribution (a circulator or diverter valve).

Interesting... now, is it a coincidence that this problem started just as the furnace is working much less due to the spring arriving, or could this have somewehat triggered it?

[Terry Achey]

Hi Augusto,

First, you have a oil-fired boiler... not furnace. Boilers heat water and furnaces heat air.;)


Second, you will likely need the "pro" to fix your problem. What you have is a heat exchanger that protrudes into the boiler water which transfers heat directly to the domestic hot water from the heated boiler water. If, as you say, the boiler water temperature is actually 180 to 200 degrees, then you should have plenty of domestic hot water when needed. From what you have described, you probably have one of the two following conditions.
Your mixing valve is faulty and is mixing too much cold water with your domestic hot water. This is my stongest suspicion since you indicated that this problem developed rather quickly.
Your heat exchanger has become coated on the inside (on the domestic water side of the exhanger) with mineral deposit. This occurs often in areas having hard water and/or well water. However, this condition generally occurs slowly over a period of years. Another symptom of this condition is a noticeable drop in pressure between the cold and hot water faucets or shower heads.
case #1 - you need the pro to replace the mixing valve unless your skilled at plumbing and heating systems.

case #2 - you need the pro to acid clean your heat exchanger which requires installing special fittings and handling and pumping strong acids.

Hope this helps to understand what "may" be happeneing. If nothing else it will help you ask the right questions with your service man.

Terry

[John O'Brien]

We had a similiar problem when we first bought this house. During the winter we couldn't take a shower until the heat shut off, or we wouldn't have enough hot water.

The coils that sit in the furtnace hot water collect deposits over time. We had them cleaned and that helped for a while. When it happened again we had the coils replaced.

Eventually we had a new furnace installed with a seperate hot water heater. What a difference that made. Unlimited hot water:)

John

[Augusto Orosco]

Hi Augusto,

First, you have a oil-fired boiler... not furnace. Boilers heat water and furnaces heat air.;)




Second, you will likely need the "pro" to fix your problem. What you have is a heat exchanger that protrudes into the boiler water which transfers heat directly to the domestic hot water from the heated boiler water. If, as you say, the boiler water temperature is actually 180 to 200 degrees, then you should have plenty of domestic hot water when needed. From what you have described, you probably have one of the two following conditions.
Your mixing valve is faulty and is mixing too much cold water with your domestic hot water. This is my stongest suspicion since you indicated that this problem developed rather quickly.
Your heat exchanger has become coated on the inside (on the domestic water side of the exhanger) with mineral deposit. This occurs often in areas having hard water and/or well water. However, this condition generally occurs slowly over a period of years. Another symptom of this condition is a noticeable drop in pressure between the cold and hot water faucets or shower heads.
case #1 - you need the pro to replace the mixing valve unless your skilled at plumbing and heating systems.

case #2 - you need the pro to acid clean your heat exchanger which requires installing special fittings and handling and pumping strong acids.

Hope this helps to understand what "may" be happeneing. If nothing else it will help you ask the right questions with your service man.

Terry

Thanks for the correction and explanation Terry! This information will be extremely helpful when I discuss the issue with my service man on Monday.

[Lee Schierer]

Interesting... now, is it a coincidence that this problem started just as the furnace is working much less due to the spring arriving, or could this have somewehat triggered it?

I would suspect that the thermostat controlling the heat for the hot water has died. If the house temp is being maintained by the house thermostat, there should be a separate themostat that tells the burner when to fire for hot water use. This thermostat may have died several months ago, but was not noticed because the boiler was running a significant amount to heat the house so the hot water load was covered at the same time. Now that the house isn't calling for heat, there isn't enough heating occuring for the hot water needs.

[Augusto Orosco]

Your mixing valve is faulty and is mixing too much cold water with your domestic hot water. This is my stongest suspicion since you indicated that this problem developed rather quickly.


So, to provide closure to this thread: I had the oil company come on Monday to perform a yearly maintenance and have a look at my hot water problem. If they couldn't come up with a solution, I was going to bring in a plumber.

To make the story short, Terry was correct. They quickly changed the mixing valve and the problem was solved. The old valve was about 10 years old badly corroded.

Thanks to Terry and everyone else who chimed in with suggestions!