Plumbers out there, solve our condo hot water problem!

This problem started recently. I am in a condo of six units. Our hot water is derived from two big hot water heaters, working in tandem. Recently the overall hot water pressure seems lower then before and now when someone else either yourself or someone else in the building also uses hot water, the flow is reduced to a near trickle. Needless to say this is a problem when taking a shower. A plumber has visited the scene. The water inlet pipe to the heaters is only 1/2" while the heater outlet pipes is 1 1/2". To evidently compensate, there is an electric pump on the inlet. The plumber thought the pump was defective and had it replaced although the new one seems smaller. However the problem still exists with no change in the symptoms at all. The plumber was called again and he says it must be for some reason the overall pressure of the water entering the building has been reduced for whatever reason as that can be the only explanation. The thing is unlike the hot I can run multiple sources of cold water without a noticeable drop in pressure although the overall cold water pressure is greater then the hot to begin with.

My thought is perhaps it's something to do with one of the heaters but they merely just heat water as it's passed thru don't they, meaning it wouldn't factor in to any pressure problems?

It sounds like the "plumber" they called in is an idiot. The 1/2" line is almost certainly a hot water recirculation line. The pump is not to boost pressure, but to move hot water through the loop. If this is the case, the line will go near the bottom of the water heater, tee'd into the drain, or if they are commercial units, to a dedicated port. You may have a problem with a mixing valve if one is required in your area to prevent scalding. Also, when you say "in tandem" are the water heaters in series or parallel? Pictures may help...

Additionally, it is very simple to test pressure on either hot or cold with a $8 gauge you can get at Home Depot. It attaches to anything that takes a garden hose connection, like a washing machine box.

Be sure the "plumber" is licensed, otherwise get someone else who is.

Agreed. Plumber is idiot.

Valve problem... or maybe obstruction within the tank(s).

A real plumber.

My house has a 3/4 inch supply, I would think that an apartment would have at least 3/4 to 1 1/2 supply. Some where there will be a T fitting, one going to cold, the other to the hot water heaters. Incoming water pressure can be tested with a pressure guage. There might be a shut off valve after the hot water heaters that someone may have fooled aorund with.

I would guess that the water pressure should not drop all that much passing through the heaters.

I suspect that the outlet is the 1/2 inch pipe, and the supply is the 1 1/2 inch.

will said:

I suspect that the outlet is the 1/2 inch pipe, and the supply is the 1 1/2 inch.

Click to expand...

That wouldn't matter. A pressure drop is a pressure drop, regardless where it occurs in the system. I still lean toward the 1/2" line being a recirc. I am curious to see some pics.

It is unlikely that it is a restriction in the tank. Likewise, unless it's a globe valve (rare, really rare in 1 1/2") or a gate valve (also unlikely) then I doubt it's a valve issue. I still say mixing valve or possibly a regulator, though I doubt that.

IIRC Mr. Hawkeye is a real plumber.

I agree that nothing in the recirculating system should reduce water pressure, including the motor that was replaced. There's a restriction in the system somewhere and it has apparently been around for awhile and gradually worsend because of your statement that the hot side pressure has always been lower than the cold. In a properly constructed system, the pressure should be the same on both sides.

A long shot, but it has happened to me -- if the system is very old and the water is mineralized, you may have mineral buildup in the system, almost always worse in the nipple (short connector pipe) where the hot water comes out of the heater. This is particularly true of electric heaters.

Again, the services of a real plumber are highly recommended.

yup yup I vote minerals. been there done that, and continue to do that;
that being; removing the ceramic mixing valve from the shower every month or two, disassembling it, and then removing the mineral chunks from the "buckets" -- little mixing-pressure-regulating indents in the valve - your design may vary.. I removed the plastic inserts (the actual spring-loaded 'buckets') in the valve completely and reassembled it, and that improved things for a while, but the big chunks still get trapped..sometimes turning the hot water off and on real fast a few times dislodges a chunk and the flow improves.,
my chunks are caused by the (flash) heater, evidently they form as the water flows through the heat exchanger, and lodge in the shower valve and the shower head. In the kitchen the hot water pressure is always good as the chunks don't get stuck in the sink faucet.
Motion (like spashing), heat, and chlorine can all make hard water precipitate mineral chunks.
I called the plumber a month ago, and asked him to cut a hole in the shower wall and install just regular ball valve faucets to replace the fancy mixer, (he seems to have disappeared now.. it's a mystery..)

anyway; anyone know of a shower valve (preferably ceramic -- doesn't wear out) that doesn't get clogged so easily for us hard water folx?

I vote with the minerals as well! This supposed "clean" water we are drinking, I think is worse than the well water of old!! Heat just makes matters worse! How old are the heaters? How often have they been drained? Have they been drained? It's amazing how fast a hot water heater can fill with crude considering how "clean" our water is supposed to be!!!! And even more amazing how fast valves can corode/plug, it's scary!!!!

As for the ceramic valve, let me know when you find one. I want to install one myself!!

A plumber (different one) found a partially closed valve somewhere in the hot water tank area plumbing and it seems to be quite a bit better although I'm not convinced it's a hundred percent fixed. Not sure what valve or where. I think the tanks themselves are fairly new.

Great. Enjoy your shower.

Glad to see the $$$ and time wasted on the recirc pump wasn't wasted on the initial call. :shrug: I see that all too often: under-qualified techs out there who perform needless work only to have someone else actually fix it.

And BIGIRON's right, I'm a licensed plumber.

Ok, problem not solved. This morning enough pressure but temperature lukewarm at best water. Plumber called back. From the words of my condo trustee, this is the problem.

"The problem appears to be part of the mixing valve being built up with sediment over time. Basically, there are 2 hot water pipes coming from each water heater that mix with a cold water pipe to keep hot water from getting too hot. There is also another small pipe that usually backflows & recirculates the water. Right now, the water is flowing through the small pipe, restricting water pressure but maintaining the temperature. When the plumber opened the valve yesterday (it should be open in a properly working system), it fixed the water pressure problem but since the mixing valve is not working properly, it restricted the hot water from coming up. So, for now, the valve is off & the water should be warm again but the pressure will be low. The mixing valve parts are so old they have to order them. The plumber is going to call me back today & tell me when it should be in & then he can replace it. Unfortunately, there aren't interchangeable parts for this so he can't use another brand without replacing the entire system & pipes & everything else."

Does this make sense? The only thing that makes me nervous is that this wasn't a problem that built up or at least symptom wise, it happened all at once. But now we are back to the original problem, you can't run two hot water sources at once.

geepondy said:

The problem appears to be part of the mixing valve being built up with sediment over time.

Click to expand...

Hey, isn't that what I said from the beginning?

You did yes (thank you) but what I don't understand if this was a build up over time problem, why the sudden failure? Wouldn't you think the water pressure would gradually decrease over time instead of apparently all at once?

A couple of things - you don't notice the incremental lessening over a period of time. Just think of the government.

There may have been a piece of mineral that dislodged somewhere in the system and lodged in another restricted place making it worse.

This kind of stuff is like an imtermittent car engine problem -- can make you crazy.

Does sound like you're on the right track tho.

Another thing I should add is right about the time this happened maybe a week or so before, the main water was shut off as one of the units had repair work done. Perhaps debris came in when the water was turned back on.

Think stroke. Gradual calciul buildup then when work was on the system, maybe a piece broke off and is causing the problem.

What Kevin said. A couple of really old houses I've been involved in (with some galvanized iron pipe) have had the "shock treatment" - turn water off, drain, turn water back on, repeat numerous times, sometimes with a little bang with a hammer every now and then to dislodge scale.

If you buy an old house and fix it up, you still have an old house.