domestic hot water heater long time to recover

[ant]

it seems like it takes a long time for my hot water heater to recover after my
DAUGHTER takes a shower. i have a side arm heat exchanger. the anti scold valve
is all the way to 145

 

[Storm56]

I too have the side arm and mine does not have a fast recovery either. Does your daughter take long showers? The only time we really notice it much is when my wife does laundry.

 

[Butch(OH)]

Side arm could not keep up with our family of 5. Installed a plate exchanger and all is well

 

[Laird]

Side arm could not keep up with our family of 5. Installed a plate exchanger and all is well

:agree2:

My plate exchanger will keep up with demand all day, but two people cannot use hot water at the same time.

 

[itn]

it seems like it takes a long time for my hot water heater to recover after my
DAUGHTER takes a shower. i have a side arm heat exchanger. the anti scold valve
is all the way to 145

I have a 40 gal wtr htr with a mixing valve. 2 teenagers and wife. All 4 can get a shower, but thats about it. Mixing valve was set by hand. Dialed down to where hot had to have some cold added. Mixing valve just has a dial, its a little touchy. Recovery time however, does take awhile.

 

[Coldfront]

What exactly is a plate exchanger? How does it work? I still don't even fully understand how the side arm works, seems to me like it would take a long time to heat a 30 gal hot water heater just off that side arm but I guess it does the job.

 

[blackdogon57]

I had the same problem with my original setup ( side arm with 40 gallon tank).
Sidearm became clogger with sand and mineral deposits from well water. I put in new 60 gallon electric tank and bigger side arm. Also put filters and softener on water lines.

No have virtually unlimited hot water and breaker in tank has never been turned on.

 

[blackdogon57]

I had the same problem with my original setup ( side arm with 40 gallon tank).
Sidearm became clogger with sand and mineral deposits from well water. I put in new 60 gallon electric tank and bigger side arm. Also put filters and softener on water lines.

No have virtually unlimited hot water and breaker in tank has never been turned on.

 

[Steveguy]

Side arm heat exchangers are a simple one tube inside another tube exchanger. They rely on thermosiphoning to circulate the water in the tank through the inner tube. Cooler water from the bottom of the tank comes in the bottom of the exchanger, is heated by the boiler water surrounding the inner tube, contained by the outer one. The warmer water then flows up the tube and returns into the top of the tank. It is important to have your piping at the top of the tank as low to the tank as possible. The warmer water doesn't like to flow back down into the tank very far, and if your plumbing is too high above the tank, it will slow the flow down alot and recovery times will increase alot. Even done correctly, the sidearm relies on a good sized tank to give you a supply of hot water, enough to satisfy your normal demand and then have plenty of time to recover. The BTU output of a sidearm isn't very high, so it takes time to recover.
A plate exchanger has a much greater surface area to transfer heat across, so its BTU output is much greater. Don't be fooled by the small physical size. If you look at one closely, you can see many layers of plates hooked together, basically on each plate, one side has hot water from your boiler on it, and the other side has domestic water on it. This gives you great amounts of heat transfer, commonly over 100000 btu, compared to a standard water heater at 30000 , and a sidearm with its small transfer area. Some people hook a plate exchanger up on the incoming cold water inlet to the water heater, tempering the water before the water heater, if your flow rate is slower, one shower at a time, it will keep up indefinately. Others will hook up a plate exchanger with a pump circulating the water in the tank similar to the sidearm heat exchanger. Some will hook up a temp. switch to the pump so they can actually control the temp in the tank just like the stock water heater, by starting and stopping the pump. This gives you accurate temp control and fast recovery time.
Iam just using a sidearm, and 50 gallon gas ,but now have more people in my house and notice that the gas waterheater kicks on with high demand times.

 

[Laird]

Side arm heat exchangers are a simple one tube inside another tube exchanger. They rely on thermosiphoning to circulate the water in the tank through the inner tube. Cooler water from the bottom of the tank comes in the bottom of the exchanger, is heated by the boiler water surrounding the inner tube, contained by the outer one. The warmer water then flows up the tube and returns into the top of the tank. It is important to have your piping at the top of the tank as low to the tank as possible. The warmer water doesn't like to flow back down into the tank very far, and if your plumbing is too high above the tank, it will slow the flow down alot and recovery times will increase alot. Even done correctly, the sidearm relies on a good sized tank to give you a supply of hot water, enough to satisfy your normal demand and then have plenty of time to recover. The BTU output of a sidearm isn't very high, so it takes time to recover.
A plate exchanger has a much greater surface area to transfer heat across, so its BTU output is much greater. Don't be fooled by the small physical size. If you look at one closely, you can see many layers of plates hooked together, basically on each plate, one side has hot water from your boiler on it, and the other side has domestic water on it. This gives you great amounts of heat transfer, commonly over 100000 btu, compared to a standard water heater at 30000 , and a sidearm with its small transfer area. Some people hook a plate exchanger up on the incoming cold water inlet to the water heater, tempering the water before the water heater, if your flow rate is slower, one shower at a time, it will keep up indefinately. Others will hook up a plate exchanger with a pump circulating the water in the tank similar to the sidearm heat exchanger. Some will hook up a temp. switch to the pump so they can actually control the temp in the tank just like the stock water heater, by starting and stopping the pump. This gives you accurate temp control and fast recovery time.
Iam just using a sidearm, and 50 gallon gas ,but now have more people in my house and notice that the gas waterheater kicks on with high demand times.

Well said.
My plate exchanger is about the size of a shoe box but will give me scalding hot water all day. The only problems I have with is as I said before only one hot water user at a time, and with hard well water it will lime up over time. With me it's one year. I have two of them and will be swapping them out every year and soaking the out of service one with vinegar to clean it out.

 

[Limestone]

Try draining the tank to clean out any sediment in the bottom

 

[odps]

plate exchanger

​

What exactly is a plate exchanger? How does it work? I still don't even fully understand how the side arm works, seems to me like it would take a long time to heat a 30 gal hot water heater just off that side arm but I guess it does the job.

here is a sample pic of a plate exchanger. (not completely hooked up in this photo I pulled off of the web) Mine is heated via OWB and my water heater is 80 gal. I have a mixing valve set 122 deg F. During heating season while the OWB is going, I simply turn the breaker off on my Hot water heater and let the OWB do its job... Recovery is instant and constant... when the kids are home from college, still no problem... showers, clothes washer, dish washer, what ever... Impossible to run the thing out of hot water...

 

[user 44856]

on/off lever + 3 minute showers