Fantini shower thermostatic mixing valve with 3 vol controls no cold water

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chickenbrown

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I'm truly stumped on this and I hope someone can help. I installed a super high end Italian made ( but sold in USA for 30 years) shower rough yesterday and after three hours of head scratching gave up!

The shower rough is a Fantini 19003903AU. Which is a 3/4" thermo mixer with 3 vol controls. It has two integral stops built in. After install I tested and found that I very little cold water into the mixer. I made sure to solder all the joins off the body and then make them up cold later so not to expose the cartridge to heat. So with both integral stops fully open I get pretty hot water out of the test vol control. If I shut the hot side I get a trickle of cold. If I open th hot up and shut the cold I get full pressure water the same temp as before ( hot but not scolding). So then I think maybe it's the integral stop on the cold side. I removed it completely. Same thing just a trickle of cold. Then I removed the cartridge itself and tested it again. Full pressure cold through the cartridge opening. So now I figure it's got to be a bad cartridge and luckily I'm installing four of the exact same body. I take a cartridge from one of these and swap it out. Same thing!!!.

I made very sure not to damage the cartridge or turn it around during the swap out so I'm sure it's in right. The house is well water but the pressure is pretty good. I don't have the tools to do a pressure test but it's for sure over 20 lbs because I cannot hold it back with my hand on an open 1/2" line.

Help!!
 

chickenbrown

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Update.... Just to make 100% sure I don't have two bad cartridges. I just swapped out a third cartridge from a brand new rough in the box. Same thing. No cold water this time. The two previous cartridges allowed a trickle of cold water.

How is this possible? Do I get 4 bad shower roughs?? I have to be missing something here?
 

Jadnashua

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What happens if BOTH the hot and cold stops are fully opened? All shower valves sold in the USA must have anti-scald technology, and many (not all) use a pressure balance spool valve inside. That will stop, or severely diminish the output unless the pressure from the hot and cold are equal. IOW, it won't work right if only one supply is open. Some thermostatically controlled valves might react fast enough to prevent loss of one supply's pressure, but a pressure balance valve is easier. When you open only one supply, (but usually not on a new valve) if it has a spool valve, it can get jammed to one side and restoring pressure won't return it to its neutral position without some help.
 

chickenbrown

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What happens if BOTH the hot and cold stops are fully opened? All shower valves sold in the USA must have anti-scald technology, and many (not all) use a pressure balance spool valve inside. That will stop, or severely diminish the output unless the pressure from the hot and cold are equal. IOW, it won't work right if only one supply is open. Some thermostatically controlled valves might react fast enough to prevent loss of one supply's pressure, but a pressure balance valve is easier. When you open only one supply, (but usually not on a new valve) if it has a spool valve, it can get jammed to one side and restoring pressure won't return it to its neutral position without some help.

Thanks for your reply. Problem solved. It was my own silly mistake. The mixing valve on these bodies has a " soft stop" in the relovution. I should also mention I didn't have the trim while testing it. Had I, I would have noticed that I just have to continue the turn to the right to get cold...... With my figures the soft stop seemed to be the end of the revolution.

Thank again
 
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