Hot water problems

Tim_12

I have been lately overwellmed with insf. hot water calls lately and from past experiances of my own I try to share with the customer, however ussually I arrive at the call and find that there is hot water at the taps and not enough at the tub, I know they consume alot more that the faucets,
Usually they are the mixing valve or one handle in the shower. Now tell me if I am wrong, I suggest they call the plumber for the fact that I seam to think it is there that is the problem, I have always recommended it that way and today a retired plumber told me that I was wrong, If there is ample hot water else where but not at the tub/shower it has to be the problem right???

cowie

Insufficient hot water

If it is a single handle valve did you check to see if it was the internal mixing valve of the tub valve?

Jackchips

Tim,

have you tried running the tub/shower valve and then going to the source of the hot water (tankless, water heater), holding onto the outlet pipe and see if it is hot. If yes, the problem is probably at the valve. If you can hold onto the pipe with the valve operating, the source is the problem.

Many tankless heaters lose the ability to keep up because of liming. This can happen in some areas within a very short time after installation.

J.C.A.

To check if it's a mixing problem....

On a single handled mixer , I test the temp at the tub, then go to the vanity. The vanity has no mixer and will give the real temp. . If the tub/mixer temp on full hot is more than 10°-12° different , I suspect the mixer/balancer . There are mechanicals at work with heated water , things grow and stop other things from moving properly. Chris

Al Letellier

hot water

Tub spouts have no flow restrictors like faucets do. They simply draw more hot water than the lav faucet will. Measure the flow in GPM with a bucket. Sounds like the tempering valve needs a flow restrictor to help the coil keep up with the demand.
If the shower works OK but the tub faucet runs out when filling the tub, your problem is flow. If the shower has the same problem, chances are the mixing faucet is the problem.
Easy as 1-2-3!

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JackFre

On-demand hot water

On Demand (I try not to use the term instantaneous) water heaters are all about flow and temp rise. The previous post about a bucket and watch for checking flow rate is right on. Also, check output temp at the water heater outlet and hot water temp as close to the shower/tub as possible and then check the temp at the shower head gooseneck. I have seen a lot of back/cross flows on house plumbing systems. I use an on-demand water heater (Rinnai Continuum) at home and the tub/shower valve can impact delivered water temps. For instance, the kids bath has a new valve and the master shower has a clapped out old Delta (I know, all I have to do is maintain the thing). With the same water temp supply to both showers (within 8' of each other) the kids get a significantly hotter shower. Old seats vs new. I represent Rinnai in New England. One of the things I like about the Rinnai is the ability to read GPM thru the unit and to confirm output temp on the digital touch pad. It reads in tenths of gal. This is also a nice feature when using them for heat. Get your flow in tenths of a gallon and delta t andyou know what is happening

To be successful in a US household with an on-demand water heater you need a fully modulating burner. With that you can then handle low flow rates (which is where the old single stage units were weak)and put a big enough burner on the unit to satisfy whole house waterheating demand. My unit modulates from 15,000-180,000btu's and .5-8.4gpm. In some very large flow systems I've used multiples and used Rinnai's controls to unify the system, so if someone has a 12gpm tub flow I can use two units and have modulation from 15,000-360,000btu and handle the flow rates continuously 24 hrs per day.