I did that in an old rusty basement bathroom, just cut out the old one, and sweat in a new one. You would need to be able to sweat pipes, as you may imagine. Not sure what steps you would like outlined- you have to access the valve body, either from inside the shower (less ideal) or from the wall behind it (more ideal). You need enough of an opeing to cut out the old valve body and make sure the new one will fit in that space, or you would have to do more extensive plumbing. You also will have to address the inside shower wall, and how you will refinish it with the new trim- if you are going from a 3 to single handle, you may well have to add tile... unless you can find one that has a large enough trim to cover the old opening! Which steps do you need outlined?

I was about to say "yes, looks good, kit is complete", but then noticed that you said you "bought the valve you need". What does that mean? did you buy a new valve and have it installed? It seems that you are either matching trim to the existing valve that came with the house, so presumably that ebay trim is right, Or, you bought the valve separately, and now you would need to make sure you buy trim that fits the new valve (if it's a different model#, mfr.#, etc.). BTW, are you sure the valve is original, or were the previous owners in the midst of replacing it, but never completed the job? Does the installation look original or recent? How old is the house? Some things to consider. This post was edited by homebound on Mon, Aug 19, 13 at 7:50

Yes--thanks for the responses--I thought that was a stupid comment that showed he didn't pay attention to what was behind that shower wall. I didn't spend any time with the plumber --didn't even hear him knock. He was not from the firm I normally call...my husband thinks they are overly expensive and that this company would be good ( it has long history of good service in our area) but cheaper. Plumber replaced two cartridges and spent less than an hour (might have been more like 30 min) at the house and charged like 250 for labor and materials--that was not "cheap" to me but didn't get price from the one I prefer... But the heads haven't been leaking for now... I know some homeowners would have done it themselves but my husband not handy that way... @geoffrey_b-----re the lifetime of a valve--yes-I know they should last longer than 15 yrs---our area does not have corrosive water---valve operating rain and 1 wall head is Moen and they do lifetime replacement to original owners--I think we had the same valve replaced when we bought the house--but maybe it was just the cartridge--we had to pay since we were not original owners...other valve for single head is Delta... We have guy very good with Sheetrock and tile but would prefer to replace w/o tile issues...

Handyman here. Just replaced a shower valve today with different circumstances, but similar to what OP is talking about. My 2 cents: 1. Trades people will most likely charge more than you think they should. This is due to many of the things people already mentioned in this thread, but also because you bought the material. Trades people often have products they like to work with because they are familiar with them. Familiar with how they install, how they perform, how they function. When you provide materials, you also remove one of the ways they pay for their cost of doing business - markups. You can judge the practice of marking up however you'd like (just like some people don't like tipping), but its standard throughout every trade you are ever going to hire. Some people are transparent about it, some are secretive. Either way, it's how everyone pays for the cost of providing any semblance of a guarantee. 2. There will always be a spread of cost for the trades. Think of it compared to a whole house - at some point, someone is going to build a house that is less expensive in order to sell it faster or more often. The only way to do that, is to compromise somewhere. That price compromise can happen in the quality, profit margin, or speed. The race to the bottom sinks all ships. When you undercut the markets evolved price, you cannibalize small business (think about Amazon compared to small local boutique shops, toy stores, or anything non-chain). If you take a loss, you wont stay in business. If you hide cost cutting measures, like hidden poor workmanship or speedily done work that will not last, you might win in the short term, but your reviews and your customers will reflect that over time. If you are able to outlast everyone else, run at a loss, and own the whole industry - well thats not good for anyone except you. 3. Costing more often means more value. The person may have been a poor salesman, but I would wager that they provided more than their competitor - cleanliness, documentation, warranty/guarantee, etc. 4. Understand that often a quick quote will be some standardized cost that the company or person is confident they can make a reasonable profit with over time. This may mean that jobs like yours, while simple seeming to you, sometimes are more complicated than anticipated. Yours may not have been, but the next one down the road might take a whole day and they would loose money. The subsidized model is similar to the way insurance companies price their products - obviously different in other ways since it's not a subscription model. To those other people in the thread saying things like: "spare me the overhead' or "its on youtube, DIY it" or "my friends a master and says it should cost this" You should be cautious when telling other people how to run their business. Your assuredness and sometimes smug responses, while protected by the anonymity or distance of online communication, it doesn't protect you from forming poor mental habits filled with logical fallacies. You come across as arrogant and ignorant. Imagine everyone one you've ever met in your life - that's a garbage sample size from which to pull an opinion when you speak to the crowd of the world online.