Recently I purchased a new Hot water machine for my shower, while the old one still worked I moved it to the guest house shower. When it was installed in the guest house it prevented the shower from having water pressure. I can unhook the hot machine and directly run the water to the shower and it works fine, but when hooked up to the machine it has no pressure. Did not have this problem when it was installed in the other shower....thoughts?

I have moved this to the DIY forum, as more likely to get an answer here.

4 hours ago, wildoates said:

Recently I purchased a new Hot water machine for my shower, while the old one still worked I moved it to the guest house shower. When it was installed in the guest house it prevented the shower from having water pressure. I can unhook the hot machine and directly run the water to the shower and it works fine, but when hooked up to the machine it has no pressure. Did not have this problem when it was installed in the other shower....thoughts?

 

Did you remove the stopper plugs from the inlets ?

 

how about some pics ?

 

11 minutes ago, NickyLouie said:

 

Did you remove the stopper plugs from the inlets ?

 

how about some pics ?

 

It’s a good shout, but the way I read it, this is the old unit relocated. 
poster. 
have you tried running it with nothing connected to the outlet and see how it flows? If it’s poor, then check the inlet flow 

if that’s good, put the incoming water onto the outlet and back flush it 

youmighthave to take the unit off the wall to achieve the last bit

Scale knocked loose moving and clogged the heater element tubes? Maybe try back flushing the heater unit. Check for a clogged inlet screen as well.  

2 minutes ago, Free the 115 said:

check the inlet flow

 

2 minutes ago, Free the 115 said:

It’s a good shout, but the way I read it, this is the old unit relocated. 
poster. 
have you tried running it with nothing connected to the outlet and see how it flows? If it’s poor, then check the inlet flow 

if that’s good, put the incoming water onto the outlet and back flush it 

youmighthave to take the unit off the wall to achieve the last bit

 

3 minutes ago, Free the 115 said:

It’s a good shout, but the way I read it, this is the old unit relocated. 
poster. 
have you tried running it with nothing connected to the outlet and see how it flows? If it’s poor, then check the inlet flow 

if that’s good, put the incoming water onto the outlet and back flush it 

youmighthave to take the unit off the wall to achieve the last bit

Sorry, made a right <deleted> of trying to reply to myself. 
you’ve already checked the flow by disconnecting the heater. 
the only other thing I can think of, is that there’s a pump inside with a blown fuse

thanks for all replies, back flushed it it seems to be working better now. 

On 9/4/2025 at 6:49 PM, wildoates said:

Recently I purchased a new Hot water machine for my shower, while the old one still worked I moved it to the guest house shower. When it was installed in the guest house it prevented the shower from having water pressure. I can unhook the hot machine and directly run the water to the shower and it works fine, but when hooked up to the machine it has no pressure. Did not have this problem when it was installed in the other shower....thoughts?

If it has good pressure with the heater bypassed, the restriction is almost certainly in the unit or its connections. Check the inlet filter/strainer first — they often clog or get debris when a heater is moved. Also confirm it’s plumbed the right way around and that there isn’t a check valve or mixing valve installed backwards.

Some hot water machines also need a minimum inlet pressure or flow to operate, so if the guest house supply is lower than the main house, the internal valve may not open fully.