hi there

I'm not good on water work, need help ! one Panasonic DH-10BM1 multi-point water heater connects to 2 sink faucets, and a Grohe shower in-wall mixer. 2 sink faucets have hot water, but shower mixer no. today adjusted the flow rate of the shower mixer, and increased the house pump pressure, the shower still not switching on the heater.

while the shower is flowing, I turn on the sink faucet at the same time, then heater is on; when sink faucet is closed, heater off. I assumed the water heater is alright.

all piping is in-wall, I could only access the connection points to the water heater, to the faucet and to the shower.

all ideas are welcome.

Remove the shower head (to up the flow), put the mixer on full hot. Does the heater turn on?

If you reduce the heater flow (inlet valve) does the shower slow down (water is actually coming through the heater).

Agree with crossy;

the first thing you should try is to remove the shower head. if you have a rose type raindance head with 50 small rubber holes then they can very easily get blocked with impuritites in the water or bits of debris from the components of the shower.

With a partially blocked shower head you are restricting the flow and increasing the pressure will not help.

So take the shower head off, and clean it with an old toothbrush. Just be careful about increasing the pressure if its not necessary as it puts undue pressure on the shower head and maybe some pipe connections that are not up to standard.

let us know if that does the trick.....if not we can suggest plan B

May be the problem is terminology!

In England we have simple taps which control water flow not complicated faucets !

Remove the shower head (to up the flow), put the mixer on full hot. Does the heater turn on?

If you reduce the heater flow (inlet valve) does the shower slow down (water is actually coming through the heater).

BRILLIANT ! at least I could locate the problem now :

- the in-wall mixer connects to I) an in-wall shower, and ii) a hand shower bar

- with the shower bar, nor the in-wall shower, turn the mixer to full, NO hot water

- detached the shower bar from the hose, turn the mixer to full, instant HOT WATER

I guess it is the time for a thorough cleaning ! the in-wall shower will be a bit tricky though !

side question - what is the best way to remove the scale in the system ? I used to apply HG descaling on the surface, but inside ?

many thanks . . .

The blockage will almost certainly be in the shower heads, the in-wall unit likely comes off so you can dismember it on the bench.

If you can get the heads apart, so much the better. Remove the bigger crunchy bits and then use vinegar to dissolve the rest.

There are a number of de-scaling products that work better than vinegar but that's something that many of us have 'in stock'. I have seen hydrochloric acid here, very effective but not something you want to get on your skin, have a look in your local hardware store.

The blockage will almost certainly be in the shower heads, the in-wall unit likely comes off so you can dismember it on the bench.

If you can get the heads apart, so much the better. Remove the bigger crunchy bits and then use vinegar to dissolve the rest.

There are a number of de-scaling products that work better than vinegar but that's something that many of us have 'in stock'. I have seen hydrochloric acid here, very effective but not something you want to get on your skin, have a look in your local hardware store.

followed through the PDF manuals and I disassembly the shower heads, and some serviceable parts of the mixer. now the shower heads are in a mug of vinegar, just let it soaps over night.

I found some unbelievable debris stuck in the mesh filter inside the shower heads, size of a small peanut. they went through the water meter, the tank, the house pump, the water heater, the mixer and arrived there. surprised me, there is no a single mesh filter along in the system.

question here - should I add one, what type and where ?

May be the problem is terminology!

In England we have simple taps which control water flow not complicated faucets !

yeah, I know, and try to be specific :- ) in the Grohe manual, it labelled as 'flow rate limiter', a small adjusting allen key nut, that pre-sets the maximum flow of water in the mixer.

I'm not good at water work, and this huge mixer far too complicated than a tap. I am learning though !

The blockage will almost certainly be in the shower heads, the in-wall unit likely comes off so you can dismember it on the bench.

If you can get the heads apart, so much the better. Remove the bigger crunchy bits and then use vinegar to dissolve the rest.

There are a number of de-scaling products that work better than vinegar but that's something that many of us have 'in stock'. I have seen hydrochloric acid here, very effective but not something you want to get on your skin, have a look in your local hardware store.

followed through the PDF manuals and I disassembly the shower heads, and some serviceable parts of the mixer. now the shower heads are in a mug of vinegar, just let it soaps over night.

I found some unbelievable debris stuck in the mesh filter inside the shower heads, size of a small peanut. they went through the water meter, the tank, the house pump, the water heater, the mixer and arrived there. surprised me, there is no a single mesh filter along in the system.

question here - should I add one, what type and where ?

Should be no need to add extra filters, you have cleaned out the likely problem now so it should be good for another 3yrs.

A lot of debris comes and grows in size like calcification, kettle fur scenario over time. The peanut didn't necessarily start beyond your water meter.

Get the thing put back together before the warranty expires!

We have a simple polyester crunchy-bits filter on the incoming supply that catches the occasional sand and grit and stops the majority of the mud that always seems to get in the pipe when they do a repair.

Before putting it all back together run the heater on full flow in case there are any more peanuts in the pipe waiting to bung up the head again.

Should be no need to add extra filters, you have cleaned out the likely problem now so it should be good for another 3yrs.

A lot of debris comes and grows in size like calcification, kettle fur scenario over time. The peanut didn't necessarily start beyond your water meter.

Get the thing put back together before the warranty expires!

ha ha ha . . . thanks eyecatcher, the installation already expired for years :-) my doubt is - on another Panasonic single point heater, it is clear that a mesh filter installed on the pipe right before the heater. should this multipoint heat have one ? just for peace of mind.

We have a simple polyester crunchy-bits filter on the incoming supply that catches the occasional sand and grit and stops the majority of the mud that always seems to get in the pipe when they do a repair.

Before putting it all back together run the heater on full flow in case there are any more peanuts in the pipe waiting to bung up the head again.

I assumed I could get this mesh filter in Home Pro. should this be installed right before the water heater, or should this be installed even before the house pump ?

You should be able to get the simple screen filter / rubber washers at any plumbing supply, they replace the sealing washer in the heater inlet pipe connection.

Something like this:-

sorry not being clear, I mean this - the housing of the mesh filter ( that came with another water heater ) :

is it a common part in plumbing supply, or a Panasonic specific part ( don't need the valve ) ?

I'm pretty sure that's a Panasonic specific part.

The rubber washer thingies are a decent substitute, just a bit harder to clean.

thanks, I guess that filter housing is a Panasonic part as well.

the beauty of this turn-and-clean filter housing - just clean it while you are in the shower, no tool :-)