Hot Water Question

[Scenic_Cruising]

We recently purchased a 2000 Gulfstream Scenic Cruiser Millennium Edition. I need to know why I have hot water without the pump running? It’s hot, but as soon as the electric pump turns on, it goes lukewarm or cold. It has me really confused and I do have the bypass set right. Anyone else had this issue? Thanks in advance!

[Scenic_Cruising]

Thanks for all your help! After removing some covers, I found the issue. Someone had replaced the pump in the past and hooked up multiple lines to the water manifold incorrectly. They even had the cold/hot water bypass hooked up wrong.

[Old-Biscuit]

Scenic Cruising wrote:

Old-Biscuit wrote:
That Suburban doesn't use a mixing valve

Does same issue...hot/warm/cold happen when using city water via hose?

Water heaters use dip tubes to direct cold inlet down and take hot off top area of water level
If either dip tube has broken/fallen off the hot/cold mix and can quickly dilute the hot out

Suburban Diffusers
Cold Inlet....#171054
Hot Outlet...#171509

Installed from exterior of tank via cold inlet/hot outlet ports

I'll check for those this afternoon. How hard are they to install? Any instructions would help. Why would my water work without the pump or city water hooked up? I appreciate you!

Diffusers are installed from the outside of tank
Disconnect water line
Remove any fittings on tank inlet/outlet
Remove the broken diffuser 'flange'
Slip new diffuser in thru the opening...reassemble fittings/lines


AS to water flow w/o pump/city water
IF you do NOT have a hose connected and the pump is OFF how much flow are we talking about?

W/O Pump ON and NO city water hose connected then flow from a faucet should only be a short burst from system pressure then just a trickle to nothing

IF--IF you have an 'accumulator tank' (small tank on cold water system) then flow would be a bit longer but dwindle after a short duration.

[Scenic_Cruising]

Old-Biscuit wrote:
That Suburban doesn't use a mixing valve

Does same issue...hot/warm/cold happen when using city water via hose?

Water heaters use dip tubes to direct cold inlet down and take hot off top area of water level
If either dip tube has broken/fallen off the hot/cold mix and can quickly dilute the hot out

Suburban Diffusers
Cold Inlet....#171054
Hot Outlet...#171509

Installed from exterior of tank via cold inlet/hot outlet ports

I'll check for those this afternoon. How hard are they to install? Any instructions would help. Why would my water work without the pump or city water hooked up? I appreciate you!

[Old-Biscuit]

That Suburban doesn't use a mixing valve

Does same issue...hot/warm/cold happen when using city water via hose?

Water heaters use dip tubes to direct cold inlet down and take hot off top area of water level
If either dip tube has broken/fallen off the hot/cold mix and can quickly dilute the hot out

Suburban Diffusers
Cold Inlet....#171054
Hot Outlet...#171509

Installed from exterior of tank via cold inlet/hot outlet ports

[Scenic_Cruising]

Old-Biscuit wrote:
Brand/Model would be helpful?

Water is HOT until you turn pump on...then luke warm...cold
How do you know it is HOT to begin with?
Does it stay HOT using city water?
Same hot--warm--cold at ALL Faucets?

Does water heater have 'heat exchanger' or 'motor-aid' system?

HOT water becoming warm/cold HAS to be diluted by cold water:
Either via WH TANK 'ByPass', via shower knobs not being closed, via clogged mixing valve.
*only places cold can get into hot plumbing lines

2000 Gulfstream Scenic Cruiser Millennium Edition. The hot water heater is a suburban sw10de. The electric element and thermostat switch are new. The propane side works flawlessly and cuts off when the water is hot. The water gets hot enough that you can't put your hand under it at every faucet. I haven't tried it with city water yet (I'll do it today.). I double checked all the shutoffs and bypass valve. It does get cold at every faucet when the pump kicks on. Where would the mixing valve be? Could a clogged faucet really cause this?

[Old-Biscuit]

Brand/Model would be helpful?

Water is HOT until you turn pump on...then luke warm...cold
How do you know it is HOT to begin with?
Does it stay HOT using city water?
Same hot--warm--cold at ALL Faucets?

Does water heater have 'heat exchanger' or 'motor-aid' system?

HOT water becoming warm/cold HAS to be diluted by cold water:
Either via WH TANK 'ByPass', via shower knobs not being closed, via clogged mixing valve.
*only places cold can get into hot plumbing lines

[jdc1]

Better check that stuff again.

[Scenic_Cruising]

way2roll wrote:
Are your winterization bypass valves off?

The bypass valves are set correctly, too.

[Scenic_Cruising]

DrewE wrote:
Verify that the outside (and inside) shower are turned off at the taps, and not turned off only at the shower head with the taps still on.

I made sure they both were and I still have the same issue.

[way2roll]

Are your winterization bypass valves off?

[DrewE]

Verify that the outside (and inside) shower are turned off at the taps, and not turned off only at the shower head with the taps still on.