I have a regular US-style shower faucet at home which looks like this:

enter image description here

I would like to convert it into a faucet that has a built-in thermostat, so that I could always have the same water temperature while showering. I see various products being sold for adding a thermostat to one's shower (such as this one from Grontherm), but I would rather not buy one if I'm not sure I can install it.

How difficult would it be to add a thermostat to my shower? Do I need a plumber or is it something I can do on my own? I'm open to hiring a plumber, as long as the installation won't require tearing down half the wall to fit in the new faucet.

  • If you have to ask, you probably will be time and money ahead to hire a plumber. You may be able to muddle through as your first DIY plumbing project (sounds like, as you're asking) but it would be a challenging one to start on.
    – Ecnerwal
    May 6, 2019 at 0:32
  • @Ecnerwal clarified in the post that I'm okay with hiring a plumber if required, but I'd rather know in advance if its an easy job or something that requires taking down half the shower wall and subsequent retiling. May 6, 2019 at 0:34
  • 1
    Is there access to the rear of the shower wall without tiles? Access panels seem to be out of vogue, though they are a fine thing to have, but a wall where you only have to fix drywall and paint, rather than tiles, after making a hole to get to the pipes is useful to know about in this context.
    – Ecnerwal
    May 6, 2019 at 2:31
  • @Ecnerwal no access panel, as this is a condo building May 6, 2019 at 2:38
  • You generally access the spigot from the other side of the wall. Knocking tile off the shower would be the hard way, and would not afford sufficient access to change the valve IMO. May 6, 2019 at 19:52

2 Answers 2


It already is that.

That's what that handle is. Depending on the type of valve, it is either

  • a thermostatic control that you rotate left/right to the desired set temperature (no choice of flow), or
  • a joystick, in which left/right is thermostatic control, and in/out are flow control. Rather like a Delta faucet.

Build like a Victorian

The knotty problem of backside access to a tub faucet is one the Victorian-era builders were well familiar with. It was "on their watch" that indoor plumbing leapt to popularity. They had a clever solution: Put a cabinet door on the backside of the faucet. In my house I can trivially access the tub-faucet backside. It's trimmed like a perfectly civilized cabinet door, and provides full access to valve backside, trap, and supply plumbing. Changing the tub faucet, drain lever or trap is a 20 minute job, and yer done.

A more cunning installation might put a bookcase there with a removable back, for instance.

  • It is not a thermostatic valve as the temperature of the water is not perfectly stable. With a thermostatic valve it will be exactly at the level you configure it to be, although the rate of flow could change. May 6, 2019 at 19:39
  • It may not be a very good thermostatic valve (what do you expect for the sub-$100 price for the thing), but the design goal of those types of valves is a set temperature. And a secondary goal is to make scalding impossible regardless of input "hot" temp. May 6, 2019 at 19:53

If no access panel, what does the shower wall with the faucet back up to? If you are lucky, it's a closet. You will have to open the wall to access the internal part of the faucet (the valve). You can do that from inside the shower or from the back side. It is normally much less expensive to access from the back. There are exceptions, such as an exterior wall or built-in cabinets, but normally to access from the back requires cutting a hole in the drywall and then repair and re-paint. What material is your shower wall? It can become fairly major to open a shower wall. If it's a fiberglass unit, opening the shower wall isn't an option. If it's tile, you can open it, but it will be expensive. You may only open a 18 inch x 18 inch hole, but you'll most likely need to re-grout the entire shower for it to match. These systems typically are bought in 2 pieces. You buy the valve or control box and buy the trim separately. I would estimate $800 to $1,000 for parts. The plumbing part itself shouldn't be very expensive. The unknown is access in the wall. I don't have enough details to help with that part. Sorry!

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.