Cold showers
February 14, 2007 4:04 PM   Subscribe

Please help me figure out what is going on with my hot water heater. I want to have a less foggy understanding of what may be wrong before I start asking either my landlord or the oil company questions.

Our apartment has what appears to be a single oil-burning appliance in the basement that supplies both steam to the radiators and hot water. When using the shower, occasionally it becomes very difficult to get anything hotter than lukewarm water out of the faucet. It seems that if you turn the hot water up higher, the water actually gets colder, as bizarre as that sounds. All I can glean from the boiler is that it was made by Burnham and it has the boiler number W-84. I can't find that model on their website, so it might be discontinued. Google finds nothing.
posted by mkb to Home & Garden (8 answers total)
I used to live in a place that had one of those. What's going on is that there's a side tank on the furnace where they keep cold water, but the side tank isn't very large. They'll tell you that a thermostat on the furnace will detect that the temperature in the side tank is going down and that the furnace will light up and is capable of providing as much hot water as you need, but I never found it to be so.

The reason that "turning the hot water up higher makes the water colder" is simply that by the time you try that you've already mostly run through the hot water in that side tank, which probably isn't very big. (Mine was 5 gallons.) It would have gotten colder anyway, just not as rapidly.

The only answer I ever found was to take my showers quickly, using a relatively small water flow. (Which made washing my hair fun.)
posted by Steven C. Den Beste at 4:24 PM on February 14, 2007

Yeah, I've got speed-showering down to a science since moving into this apartment. One thing that I've found to be helpful is to make sure the radiators are on before taking a shower.
posted by Ruki at 4:28 PM on February 14, 2007

I can't seem to find a side tank at all though. The landlord's heater has one, but not the one labeled as 2nd floor. Do they make tankless oil-burning water heaters that double as radiators?
posted by mkb at 4:33 PM on February 14, 2007

Can the water be made hotter, so that it lasts longer?
posted by theora55 at 6:03 PM on February 14, 2007

Just a guess. I had a hot water heating system. And it had a small tank on the side. It was an expansion tank. You might google it.
posted by JayRwv at 6:16 PM on February 14, 2007

mkb, you probably have a so called tankless heater, which is a coil of tubing in the boiler firebox, or even in the main boiler, to which the hot water distribution piping is attached. In theory, if this was correctly sized at installation, all the units in your building should be able to pull hot water, nearly endlessly, as hot water will be produced on demand, by the furnace cycling to keep the output temperature sensor on the hot water loop up to set point.

As an economy measure, or perhaps as a safety intervention, the furnace controls could have been adjusted to limit the temperature to which water is heated, so that when you get to a point where the furnace should be delivering hot water, it is in fact cycling off, thinking it has done all that is needed to service demand. Usually, there will be a "dead band" period, to prevent the continual re-firing of the boiler firebox in short bursts, so once the burner shuts down, it will stay shut down for several minutes, during which time you give up and shut off the hot water. You could check this, by leaving the hot water running, and if it later heats up again, this is most certianly what is happening.

But it could also be that simple age is catching up with the system, and something as simple as scale deposits accumulated on the heating coil are stopping it from effectively transferring heat. Most boiler systems are supposed to operate with scale control additives, or make other provision to control or remove scale buildup, as part of regular operation, but it's no uncommon that older systems that don't recieve regular maintenance quickly foul, especially in areas where the feed water is hard (mineral laden). In most states, only licensed boiler repair persons can make repairs to such systems.

If you aren't getting adequate hot water, as a tenant, you have to focus on that as a complaint with your landlord. Be reasonable, document your claims, put it in writing, be persistent and yet civil. Give the landlord reasonable time to make repairs, and be in touch immediately as to whether such repairs have corrected your problem.

But also recognize that your ultimate recourse as a tenant is to move, if the circumstances of your apartment aren't satisfactory.
posted by paulsc at 6:30 PM on February 14, 2007

What paulsc said regarding the possibility of cycling off and dead band. If not, though, it may just be undersized for your building's heat loads. It makes sense that, once you use up the initial store of hot water, raising the flowrate lowers the outlet temp.
Q = mc(Th - Tc),
Q = thermal power (maxed out for your boiler),
c = specific heat capacity (essentially constant),
Tc = the cold water temp into the boiler (constant).
So if m, the flowrate of the water, goes up,
Th, the water temp out of the boiler, has to go down.
posted by ctmf at 11:22 PM on February 14, 2007

Also, second paulsc's recommendation re: not your job to know why you aren't getting hot water. Your complaint is simply that you're not. Landlord's job to troubleshoot and fix.
posted by ctmf at 11:26 PM on February 14, 2007

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