How to Install an Anti-Scald Shower Valve | Ask This Old House

you can't relax in the shower richard whenever sun returns on the water in the kitchen you get scalded is this our bathroom right here yes it is all right well i've heard this complaint before and i've seen this as the culprit before this is actually called a three valve this is a standard tub and shower valve up until the late 60s in america it has a hot water pipe inside the wall it goes to this hot valve a coal pipe right here here's your hot and cold handle now the water comes together to this point this is called the diverter you can turn the handle and the water will come out through the tub spout or you turn it the other way and i'll go out through the shower head right here so when you first set these the hot the cold and it mixes right here it works fine but as soon as somebody uses any other plumbing fixture in the building what's going to happen if it's cold water you're going to drop the cold water pressure say somebody flushes the toilet or use the kitchen sink now if that cold water pressure drops all of a sudden hot water is the strongest pressure and all hot comes into this point and you get scalded oh yes it's awful so what i want to do is i want to replace this three valve with a valve like this this is called a single lever pressure balance shower valve all right you set the temperature you want okay when you set it it'll stay right at that temperature no matter what happens in the building all right the way it works is this there is here's a cutaway so you set the temperature right here so imagine you've got the hot water coming in here the cold water pressure right here you set the temperature by turning the handle this way and it mixes just like the other one did but if i turn this a little more see right here this is the really important part there's a little piston right here you see this piston and go back and forth and that adjusts for pressure so now imagine that you flush that cold water from the toilet this pressure would drop well what will happen is this piston will move in such a way that it'll slide and actually shut down the hot water pressure to match the cold and that means you're going to end up with the same temperature a little lower pressure but you'll never get scalded oh that sounds great richard but this is is much much smaller than those aren't are you going to leave holes in my wallet well this is not the first three valve that has need to be replaced and you really don't want to replace all this uh tile so the manufacturer makes this this is really ingenious it's a cover plate that'll allow us to remove these handles it'll cover the holes and when we're done it's going to look like this on the wall what do you think oh that looks great all right it starts by us turn off the water down the basement all right with the water off i now want to get rid of these handles and these escutches these chrome pieces now behind the buttons the hot and the cold there are some screws that will hold the handles on that's a phillips sometimes these can be miserable they've been in for a long time so the handle will not come off so what i'm going to use is this it's a handle puller a tool made just for this reason and now i just tighten the screw and that should pull the handle back good make short work of it this is called the escutcheon and now i want to remove the stem unit from the valve body itself for that i use a pipe wrench okay okay there's the stem unit and now we're flush with the wall i just need to do the same for the diverter and the cold all right so we have the stem units removed and now i got to get the valve body out of the wall and i got to cut the wall open now here's that repair plate i could just hold it up right here and trace the outside but the manufacturer actually makes a template and now you can see the witness lines right here and i've made marks at the center line of the old valve both vertically and horizontally and i just line them up and i trace the outside and that gives me the perfect place to cut the tile what i use is a masonry bit to drill strategically placed holes in the tile okay so now i'm going to remove the rest of the tile using this oscillating saw with this carbide blade i gotta tell you john they literally don't build them like this anymore this is what they called a mud job not just a little piece of sheetrock this was a piece of metal lath see the metal and this was all the cement built inside here and then the tile over the top of it so now i got to get the valve out of this i'm going to actually cut with a reciprocating saw in two places and get the old valve out okay so there's the old valve body out now i just need to dry fit all the connections to the new valve so joan your single lever pressure balance valve is now in the wall and i'm ready to solder it all together but before i do i want to pull this spindle out because these have parts in it that can get damaged that's that pressure balancing spindle right there all right here's our connections that we have our hot supply our cold supply our connection up to the shower head and the connection down to the tub spout all right so it's now in place i've cut them all cleaned all the pipes cleaned the fittings and i've added flux to them and now i want to solder it before i do i want to be sure i don't have any damage inside i want to just add a little water inside the wall because i'm going to put my torch in there and that is always a little scary so here we go all right john i reinstalled that spindle and turned the water on downstairs and guess what we don't have a leak that's good excellent you've done that many times once or twice and now we just want to check that the valve works correctly so now that's cold hot just like it should be all right so now it's time to trim the valve out and so here's this cover plate now this is stainless steel it has stainless steel screws has these two spanners and these will actually fit in behind the wall and as i tighten up the screws it'll pull that tight i want to put a little bit of putty right here at the back side to make a nice water tight seal right here are you going to put the putty all the way around richard actually no just at the top right there we're worried about the water coming down the wall gravity's working to our advantage you know it's not going to come up okay so here we go let's get this into the wall all right so now i'm going to install the escutcheon plate and that's going to give you the indicator dials between cold and hot here's the diverter that's going to determine whether the water goes down to the tub spout or up to the shower head right so i have these two screws i just have to line this up and before i go any further i want to add this gasket again from the top so that no water comes down in behind the wall good all right before i put any more of the trim on i want to set what they call the safety limit i want to make sure that the water coming out of the shower head never gets any higher than about 120 because i can scald people so what i do is i turn it and see at full open how hot the water is i have a digital thermometer you're 135 135 that's way too hot all right so what i do a simple screw right here that i can turn in and that limits how far we can turn that spindle let's try that and see how we do 116 118 118. i got lucky this that's good all right so your limit is set and now we just have to put this cap assembly on right here okay and the handle goes on oriented to the top right where it says off stainless steel phillips screw goes right here all right just cover that screw up with an index good and i'll just clean up the last of the putty here that's sticking out okay you got a rag there i do super okay let me just clean it up give it a little buff what do you think oh it's looking great richard yeah it's shining up nicely i think it's time for you to give it a test drive okay now turn it to cold yeah all right turn it right around to hot be sure that it's hot now let's try out the shower the diverter the diverter's right at the bottom slide it over careful don't get wet all right turn it off gotcha all right this is really fabulous thank you so much it have a nice safe shower plenty of room to work huh well that job turned out to be a little tougher than i thought getting through that old mud towel was unbelievable that lath was so sharp i cut myself to smithereens yeah the cement is hard and the wirelab is brutal right you know but that tile still looked as good 50 as late as the day it was installed the other thing is once i got the thing open i don't know if you saw it but there was a stud on each side so there's no room to cut the pipes or anything nothing behind it sometimes we have to cut an access panel behind it if there's a closet or something like that not so in this case well that you know that trim plate saves you a lot of trouble for right to re-tile so we we installed that uh that style trim plate but they have some choices i want to show you here there's a little more decorative one right here you put this on and then it gives you a couple of different choices for handles this one or this one okay and what about code i mean what does the code say about these valves well new construction you have to put them in by international code and that's a with good reason and when it comes to remodeling well if you're renovating a bathroom you should have a building permit anyways but in some jurisdictions they don't demand it most of the time they will say that you have to put in an anti-is called balance well it'd be nice to have that valve behind the wall right and once it's in you're going to have that adjustability from against pressure fluctuations but most importantly is to set that temperature limit to prevent against high temperature coming out through so if you don't set that limit a valve like that could still cause a skull there's some chance you could yeah you're going to be reduce the chances but there's always the limits much safer to set that alright well as always good information thanks guys and until next time i'm kevin o'connor i'm tom silva i'm richard and i'm roger cook for ask this old house don't go over the limits

Channel: This Old House

Views: 1,166,415

Keywords: This Old House, Ask This Old House, DIY, Home Improvement, DIY Ideas, Renovation, Renovation Ideas, How To Fix, How To Install, How To Build, shower valve, valve, safety and prevention, anti-scald valve, safety valve, plumber, plumbing, home repair, renovation, do it yourself, diy, norm abram, tom silva, richard trethewey, tom silva this old house, tom silva house, tom silva construction, tom silva tools, tommy silva

Id: b6Pk7RQA9ag

Length: 11min 25sec (685 seconds)

Published: Sat Mar 05 2016