Fix for Delta shower hot water problems?

[BarkityBark]

I have 2 single-handle Delta shower controls in two showers in my house and neither one regulates the hot water correctly. I've cleaned and changed out the valves (RP19804), but this did not solve the problems.

In one shower, pure hot water will not come out of the shower head (it only gets luke warm), but it comes out of the spigot hot. In the other shower, pure hot water will not come out of the spigot, but comes out of the shower head hot. Frustrating!!!

The house has a hot water circulating pump system, if that makes any difference. Also, the cold water supply pressure is on the high side. Perhaps hot water pressure compared to cold water pressure an issue here?

And yes, the scald adjustments are already all the way over to "hot".

Unless someone can come up with an answer, I will be forced to tear out the single handle Delta's and go with a 2-handle valve. If you recommend this option, which company makes a mid-priced model which is worthy?

 

[Jadnashua]

There should be no temperature difference when switching from the tub to the shower other than the shower will fall further, and cool off a bit on the way down verses the tub spout to the tub.

While you might be able to find some, a 'plain' 2-handle shower control valve would not pass any inspection or code in the USA...all replacements must meet the anti-scald requirements. There are some two handle controls, but the two valves are not for the hot and cold...one is for the volume (both) and the other adjusts the temperature. At the top end, that temperature control is thermostatic verses a standard mixing valve.

If the pressure between hot and cold supplies varies significantly, it can literally shut off the hot at the extreme. For chance, do you have a tankless system? That can reduce the pressure/volume on the hot side verses the cold side. ANohter thing could be if the valves you installed have maintenance shutoffs, they both may not be fully opened. To get to those, if they exist, you usually have to take the trim off.

 

[Sponsor]

 

[Reach4]

While you might be able to find some, a 'plain' 2-handle shower control valve would not pass any inspection or code in the USA...all replacements must meet the anti-scald requirements.

I expect you have again wandered beyond the limits of facts.

 

[Jadnashua]

I expect you have again wandered beyond the limits of facts.

Plumbing codes used in the USA all require antiscald tech on a shower (not a tub, but this is a shower/tub). It doesn't preclude someone from selling one in most states, but it would not pass a code inspection. There are standalone, inline antiscald devices that could be used with a 2-handle 'plain' tub/shower valve, but I did specify a 'plain' valve (i.e., one without that built in). NOw, what one does in their own home, there aren't plumbing police, but it won't pass an inspection if you're following the rules and getting one (might be an issue during resale, too).


https://inspectapedia.com/plumbing/Hot_Water_Temperature_Laws.php

 

[FullySprinklered]

Do you have a functioning check valve on your recirculation system?

 

[Reach4]

Plumbing codes used in the USA all require antiscald tech on a shower (not a tub, but this is a shower/tub). It doesn't preclude someone from selling one in most states, but it would not pass a code inspection. There are standalone, inline antiscald devices that could be used with a 2-handle 'plain' tub/shower valve, but I did specify a 'plain' valve (i.e., one without that built in). NOw, what one does in their own home, there aren't plumbing police, but it won't pass an inspection if you're following the rules and getting one (might be an issue during resale, too).


https://inspectapedia.com/plumbing/Hot_Water_Temperature_Laws.php

I looked at your link. I did not see that BarkityBark would be prohibited from putting in a 2-valve shower control. Maybe there is something more explicit.

 

[BarkityBark]

Do you have a functioning check valve on your recirculation system?

What would it look like and where would it be located?

 

[FullySprinklered]

What would it look like and where would it be located?

It's a brass thing on the down pipe near the water heater, ending into the bottom of the water heater. Looks like my ex-mother-in-law's goiter.