My old multipoint heater supplying one shower malfunctioned and decided to replace the unit with MAZUMA P-STREAM PLUS2 6,000W from Homepro. Otherwise all good and they installed small ball valve before the unit and new connecting hoses but for some reason water pressure disappeared in the process. If I turn the shower tap full hot there is barely no pressure and no flow. Cold supply is good with plenty of pressure and flow. With the old heater the pressure was much better and wondering what went wrong?

 

Could it be the ball valve limiting flow or the connecting hoses which seem to have very small diameter hole the water go thru but these are standard size with 1/2" thread right?

 

Any advice on where to start troubleshooting appreciated.

I have the same type and flows fine, check the valve. Easiest is to buy a small brass connector to directly connect the two hoses together so you can check the flow without the heater in the circuit.

 

Also, check if there's a plastic tiny filter inside the inlet of the heater. Somchai the factory worker cold have forgotten something there.

Sometimes (for whatever reason) they use seals/washers with a tiny hole in it. That would be my bet. 

 

As mentioned previously, filter screen another good bet...

Thanks, did check the connections and try different better quality connecting hoses as well without luck. 

 

Then had a closer look on the pipe going from the heater to shower and as the pipe end is deep in the wall (hate this Thai style to fix tiles over 2 inch thick pad of mortar) there was old extension pcs that were corroded and blocked by sediment or rust deposits. Took me good hour and half to dig the pipe end visible and wrestle those extensions out and remove the shower mixer and flush the pipe and replace with new extension pcs.

 

The decided to replace the old mixer and shower head as well while I was at it. Works well now and the pressure is much improved. 

 

Still need to decide what to do for those ugly holes in the wall. 

 

 

Nice work. You might be able to get some chrome or stainless trim rings. 

 

 

Thinking of just fill them with grout and then dig them out after a decade again ????