Question on two water heater system

[kintla]

Quick background: my father in law lives in Denver. He has two hot water heaters and a recirc pump. One heater went out a few months ago, so I isolated that heater, shut off the recirc pump, and he ran off the good one until he got a new heater installed.

I came back over to his place recently after the new heater was installed and he mentioned that his large jetted tub fixture wouldn't get hot, just warm. Also, master shower would be erratic with water temp. I went down to his mechanical room and the plumber who installed the heater had all of the shut off valves open.


It looks to me that the system was originally plumbed to be run in either series or parallel. Am I wrong in this? Would having all of the shut off valves open cause the problems with water temp?


I just closed the hot water out on first tank and cold water in on second tank to put them in series. Best option here?

Attached pic is how plumber had it originally. I'm not a plumber but am almost positive this is screwed up. The plumber blamed the warm water at tub on a bad mixing valve, but it is a tub only fixture with a hot and cold handle. This wouldn't have a mixing valve, right?

I am having difficulty uploading a pic. Both tanks have hot out/cold in lines, and there's a jumper from hot out on first tank to cold in on second. Every line has a ball valve. I turned off hot out (downstream of the jumper line) on first tank and cold in on second and left the jumper open.

 

[Jeff H Young]

there could even be by pass valves installed . so yes opening or closing of valves does effect operation. Its no telling how its plumbed youll need to figure out like you been . Series or paraell Ive seen argument for both havent installed a pair of heaters in decades Series is easier to install paraell the piping is supposed to be ballanced a certain way so im told and have tried to do my installs. I never had complaints so I guess both worked ok , but had some doubts on the paraell

 

[Sponsor]

 

[kintla]

there could even be by pass valves installed . so yes opening or closing of valves does effect operation. Its no telling how its plumbed youll need to figure out like you been . Series or paraell Ive seen argument for both havent installed a pair of heaters in decades Series is easier to install paraell the piping is supposed to be ballanced a certain way so im told and have tried to do my installs. I never had complaints so I guess both worked ok , but had some doubts on the paraell

Have you heard of dual tanks plumbed to run in either series or parallel depending on which valves are open or closed? This part has me stumped. I'm pretty sure it was running in series originally because the one that went out was in rough shape while the other looked almost new even though they both where probably 20 years old. My father in law doesn't use much water, so that second tank probably has never kicked on.

 

[WorthFlorida]

A recirculating system used a bypass valve from the hot to cod at the furthest faucet from the water heater. It may be stuck open passing cold water onto the hot side.

The theory on two tanks connected either in series or parallel is a forever debate. In series the first tank will do most of the heating. In parallel the plumbing has to be nearly identical so an even amount of water is drawn from both tanks. If I had to set up the system, I would go in parallel. It would be equivalent to a 100 gallon tank (2-50's) with two elements heating water at the same time to recover.

The best solution today is to use a tank booster. One tank set to 140º and the tank booster (a mixing valve) is used to cool the water down to 120º as it leaves the water heater a 50 gallon tank at 140º would be equivalent to 90-100 gallon tank.

 

[Fitter30]

Parallel reverse return ( first in last out) is the best way to pipe two heaters especially when one is new or different sizes / brands. Series the first heater ends up with the majority of the minerals and won't double capacity.
With recir there is a check valve in the return that might be sending cooler water back into the faucet.

 

[kintla]

there could even be by pass valves installed . so yes opening or closing of valves does effect operation. Its no telling how its plumbed youll need to figure out like you been . Series or paraell Ive seen argument for both havent installed a pair of heaters in decades Series is easier to install paraell the piping is supposed to be ballanced a certain way so im told and have tried to do my installs. I never had complaints so I guess both worked ok , but had some doubts on the paraell

Have you heard of dual tanks plumbed to run in either series or parallel depending on which valves are open or closed? This part has me stumped. I'm pretty sure it was running in series originally because the one that went out was in rough shape while the other looked almost new even though they both where probably 20 years old. My father in law doesn't use much water, so that second tank probably has never kicked on.

 

[kintla]

Thanks for replies. I adjusted the valves so the tanks are set up in series and everything is working as it should. Cold in on first tank, hot out to cold in on second tank, hot out of second tank to house.

Still can't believe a licensed plumber screwed it up like that and then blamed it on a mixing valve in a two handled tub faucet.