It does sound upside down. The basic way to fix that is to shut off the water to the house, remove the handle, then remove the cartridge, and flip it. There are plenty of videos on YouTube about changing cartridges. Just follow those, but the idea is just to flip the cartrige. It may also be a good idea to simply replace the cartridge with a new one if you're going to all that trouble.

yes, the handle or cartage is installed wrong.

depending on the handle/brand you might need an allen wrench, smaller flat, head or philips head screwdriver to release a set screw in addition to an adjustable wrench. it isn't all that hard to do but you will need to shut off the water.

it will be easier and cheaper for you to buy the tools and watch youtube tutorials than to hire a plumber or handyman.

Warning to OP: if you remove the cartridge there might be a pin that gets removed. I always tie a string/thread to the pin while it is still in place and attach the other end of the string to the faucet/spigot so that if I accidentally drop the pin (since it is small), it doesn’t drop into the space behind the shower wall where I can never ever retrieve it. I’m sure there’s a way to get a new pin but you can’t turn the water back on until you do so the stakes are high!!

Check the cartridge for damage, and replace if necessary.

The “barely gets hot” sounds like the mixing valve on the cartridge could be stuck.

Could be upside down but that wouldn't prevent the water from getting more that just warm. Most states require the mixing dealybob inside the housing , to be set a point that it won't scald when it's all the way over to hot. I find that set to low for me so you can adjust this so you'll mix more hot than you currently are. Personally and especially if you have kids, I wouldn't totally move it to the hottest position but somewhere hotter than you have now.

The handle shouldn’t matter. Even if it is upside down it would still have full rotation, but just wouldn’t match any markings for hot and cold. This does seem like exactly what o got when I accidentally installed the cartridge upside down. I did recognize the problem and fixed it immediately but maybe someone else didn’t.

I would also encourage the advice to replace the cartridge. Aside from it being something that needs to be replaced once in a while and is likely overdue, the seals are not really designed for removing and replacing. If you just take the current one out and replace in the right direction, you may have leaks.

Please google the name on the valve and check for "Scald-Guard or something similar. It's a feature that prevents children or mentally deficient adults from burning themselves. In my experience there is a plastic ring with a tab that stops the handle from turning past a certain point. You .entire it goes 90° in one direction and 180° in the other. That's exactly how scald-guard works on a Delta faucet.

I agree. It’s definitely the dealybob

The cartridge being upside down is the issue. The handle often fits only one way, but the handle position itself isn't the issue, just an indicator. And, if the normal rotation is from off at the 6 oclock position, to super hot at the 9 oclock position, then it's certainly possible that the rotation is the same, but the off is at the 12 oclock position because the cartriges's openings are offset from where they are supposed to be.

First person to mention the temperature limiter to prevent scalding. You get my vote.

It's a new tiny home. Why would they replace the cartridge?

It's more likely that there is a temperature limiter on the mixer that is preventing more hot water. A simple adjustment will fix the issue.

> It's a new tiny home. Why would they replace the cartridge?

Is this the argument we need today? First, people often call their home "new" even when it's not. Second, I said it may be a good idea, so OP can decide for themselves if it's appropriate.

And no, it's not the hot water limiter.

This was going to be my suggestion as well. The max temp they’re supposed to set them to by code is definitely too low for me. OP-Google your faucet brand to see how the stop position works to avoid a bunch of trial & error. You likely won’t need anything other than a small alan key for the set screw, and maybe a screwdriver.

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If it is a Moen cartridge, all you have to do is take the handle off and spin the shaft over and then put the handle on the right way.

They said ‘check for damage’ as it sounds like the original installer did not install it correctly in the first place. This is just good troubleshooting.

Like a few others have said, it's likely just a temperature limiter. I don't know what make/model shower valve you have but they are pretty much all the same. You can see the instructions for setting this on a Moen in step 5 of this document https://www.google.com/url?q=https://www.moen.com/shared/docs/instruction-sheets/ins2153c.pdf&sa=U&ved=2ahUKEwjc-O2mgYb7AhXprIkEHWMUBpcQFnoECAoQAg&usg=AOvVaw1XFxpNUNJkcchf5HjvznbD. YMMV

Could be the thingamajig, though.

First try adjusting the mix valve settin. It’s similar for most, but look up a video for your specific brand. Generally you remove the handle (loosen the set screw and pull it off the valve stem) and then there’s a toothed ring with a stop. You pull the ring forward, turn it to permit the handle to rotate further (i.e. more hot water is allowed) and push it back in the new location. Temporarily slide the handle back on and rotate it to see if you get more heat. If not, repeat and try again. Make sure you set it so it can’t be turned too hot, to protect children or guests from scalding themselves. Once it’s set where you want, tighten the set screw again.

You know what would go a long way in communicating the context & details of your problem?

A picture.

Thank you! I cant seem to find an allen key that will fit. Ive tired 4 different sets, aling with some handheld driver with the different inserts. Im stumped

Diy wont let me post a picture without taking down my post :(

Post it to IMGUR and link the URL here.

Jesus fuck, has the internet become so technically illiterate? We used to be kings.

When I had to replace mine I bought a new set of Allen wrenches at HF because I needed longer ones. One was too small, another too big, the one in between didn't work either. Then I compared the long one to the short one in the same set and it was a different size! If there is an Allen set screw on your handle one size will fit it if it is made properly. I have mine set all the way to hot, my water heater only goes to 140, in winter I turn it full hot until it is hot to save water, then adjust and step in.

It is more likely the scald protection

If it truly is a "new" tiny home. The square footage cost on those warrent a call to the builder. Tell him to get his ass over and fix it.

try metric and sae sizes. it might be torx but i don't think so.