How do I fix fluctuating water temp in shower?

[malbert73]

Hi everyone -
We are struggling to control water temp of shower. I've added one way valves and expansion tanks on hot and cold side to avoid backwash of hot down cold line. That's helped a little. Still fluctuates which I think is from higher pressure in hot water tank and fact that it's mounted "uphill" under cockpit. Still varies from very hot to cooler as water pump cycles on and off.
Only solution left I can see is to add a small mixing tank (like 3/4 gallon) after shower faucet and have hose for shower come out top. It will buffer the varying temps that seem to average ok but never be just right.
Any other solutions out there?

Thanks!
Mike



Sent from my iPhone using Cruisers Sailing Forum

[mikemenza]

Delta makes a single handle temperature correcting shower valve. They don't work very well at pressures under 30psi...

have one in the house, flushing toilet or starting the dishwasher.. it keeps temp even while the pressure changes..

[malbert73]

Great idea! May have to try it. I guess I'll have to see if my pump setting is >30 psi

Anyone out there use this valve on their boat?


Sent from my iPhone using Cruisers Sailing Forum

[sailorchic34]

Lots of temperature control shower valves on the market. You want a pressure balanced type or thermostatic shower valve. Pressure balanced shower valves are a bit smaller, but control the pressures to hot and cold so that changes in pressure does not change temperature.

Delta makes a good valve. Any big box store in the US would have them.

[jkleins]

We just replaced ours with a Delta two handle control. It is great for maintaining temp but also convenient because you can set temp and then turn it off completely to save water without having to reset handles. Doesn't have the drip that the on/off switch on the handle used to have.

Jim

[sy_gilana]

You have two separate accumulators, I think the problem is there.
Unsually it is pump > accumulator > split to cold and to water heater, then join at mixer in shower. Th only check valve you NEED is downstream from the pump.

KISS.

FWIW...

[wrwakefield]

Malbert 73,

Along with the other good, practical advice you have received, you could also put a mixing valve at the water heater output side to set a 'constant' [and usable at the tap] temperature coming from the water heater.

e.g., Our 11 gallon IsoTemp water heater is very well insulated, and approaches engine coolant operating temperature after an hour of motoring. [~185°F] That is hot enough to cause injury. The mixing valve blends cold with the hot from the tank upon demand resulting in 120°F on the hot side. [You set the temp...]

Having a stable [and usable at the tap] hot water temp will also help reduce the fluctuations you are experiencing since less mixing will need to occur at the shower valve...

With this set-up we don't experience the fluctuations you describe, but we also have a variable speed water pump that delivers a reasonably constant pressure without using a pressure tank.

[Side note- check the pressure in your pressure tank; it should be 2PSI below the cut-on pressure of your water pump, otherwise it may be exacerbating your problem. This is measured when the pressure tank is empty with the water pump off and pressure relieved in the plumbing system (open the taps until no more water flows)...]

I also agree that a temperature regulating shower valve would be a great thing to install.

That, with a mixing valve at the hot water heater so you aren't piping superheated water [a temp you would never use...] through the plumbing unnecessarily, seem like an ideal set-up.

Best wishes stabilizing your shower temp.

Cheers!

Bill

[Cruisingscotts]

Do you have a check valve in the cold water supply to your water heater? If not you can get mixing between hot and cold depending on whats being used and how your plumbing is setup. Thermostatic mixing valves are fine but you will loose some flow on a low pressure system vs just having hot and cold running thru seperate valves to a common valve and shower head.

[malbert73]

Great advice all. Yes have tried a bunch and the worst was accumulator tanks on hot and cold side. I do have a check valve as indicated. Seems like a mixer at the water heater and a hydrostatic valve would be best.


Sent from my iPhone using Cruisers Sailing Forum

[wsmurdoch]

I have had good luck with this Watts USG-B mixing valve mounted in the head. The arrangement is cold in, raw hot in; cold out, tempered hot out. The parallel in and out ports make installation easy. 3/8" connections fitted my fittings. I set it to my wife's hot shower temperature. She just uses the hot water alone. I add a little cold.

Plumbing-deals.net Your on-line source for plumbing fixtures & supplies

The only problem is that the thing has tiny strainer screens in the inlets. The hot side plugged annually with lime flakes from the water heater because of the hardness of our marina water. This year I removed the hot screen and installed a larger diameter screen in the 1/2" piping upstream of the mixer.

[Pelagic]

best solution on a boat with fluctuations in pressure is to forget about a mixer and go with hot and cold taps

Then find tiny ball valves that screw into shower head at the flexible hose, so the two taps are preset to desired temp and you just turn on at the flexible shower head.

Also helps to conserve water to, if you are taking navy showers

[seasick]

Same as Cruisingscotts, I very recently solved this issue on my boat which has separate hot and cold valves at the shower by adding a check valve (one way valve) to the cold water supply line just before the shower valve rather than the supply to the water heater. I use a flex hose (dishwashing hose) as found on kitchen sinks for my shower head and when I would shut it off at the nozzle the greater pressure on the hot water side, forced hot water down the cold water supply line such that when I turned the shower nozzle back on the water was scolding for a bit. The inline check valve completely solved the problem.

[svthreecheers]

Whats a Navy Shower ??
Cheers
Siggi

[deblen]

MOEN with moentrol temp/pressure balance.
Lifetime warranty.
Bathroom Tub and Shower Faucets by Moen - Shower Only

[Stu Jackson]

Originally Posted by Pelagic

best solution on a boat with fluctuations in pressure is to forget about a mixer and go with hot and cold taps

Then find tiny ball valves that screw into shower head at the flexible hose, so the two taps are preset to desired temp and you just turn on at the flexible shower head.

Also helps to conserve water to, if you are taking navy showers

Yes, this works very well for us and has for over 17 years.

Here's the part:

Grohe faucet/shower handle replacement w/picture

Scroll down for the picture.

It doesn't shut the water off 100%, there's always a small amount of water that keeps flowing, like maybe 1%.

What this means is that there is always a little water running through the pipes and the water temperature stays remarkably constant, during any length of shower (i.e., navy shower or extended one, like until your hot water runs out! ).

It is simple, doesn't involve expensive parts, needs no tools to install...

We use it with our two handed (separate hot & cold faucet) head sink.

KISS.

Good luck.