a friend has a Combi and wants to fit a good shower. In order to use one of those things with a 200mm "plate" with holes in it (not an ordinary shower head) what volume of water does it need? I can measure with a bucket under the bath taps. Ta
Flow and pressure for a "drencher" shower
- Thread starter JohnD
- Start date
Hi John.
I have a 2.5 bar pump with 2 x 8 inch drencher heads; don’t know what the min flow requirements are! They are fabulous to use but looking at the spec, mine requires a min 0.5 bar; not difficult to achieve but with, drencher heads, the volume is all important & with no pressure, satisfaction may be marginal. According to my pump spec, it will deliver between 10 litres/min @ 2.2 bar to 50litre/min @ 1 bar; I suspect my system equates very near the high pressure end but, in truth, I could easily live with 1/2 the pressure but maybe I'd drown
.
I don’t have any experience with Combi’s or their delivery/pressure rates but I would say if you can get 5+ litres a minute it will be fine, anything less than 3 litres/min will probably be marginal & dissapointing. Hope this is of more use to you!
I have a 2.5 bar pump with 2 x 8 inch drencher heads; don’t know what the min flow requirements are! They are fabulous to use but looking at the spec, mine requires a min 0.5 bar; not difficult to achieve but with, drencher heads, the volume is all important & with no pressure, satisfaction may be marginal. According to my pump spec, it will deliver between 10 litres/min @ 2.2 bar to 50litre/min @ 1 bar; I suspect my system equates very near the high pressure end but, in truth, I could easily live with 1/2 the pressure but maybe I'd drown
. I don’t have any experience with Combi’s or their delivery/pressure rates but I would say if you can get 5+ litres a minute it will be fine, anything less than 3 litres/min will probably be marginal & dissapointing. Hope this is of more use to you!
So are you commplimenting, commenting or jus taking the **** ? or what? do enlighten me!
If you can do that, youve got a serious medical problem my friend!
I held back on posting as I thought sure someone with more knowledge & experience would advise; so if your so ufkin knowledgeable, where the ufck is your contribution to Johns post? so why not get technical & advise away?
I’ve tried to help someone whose a regular contributor & who, so far, has got only a comment bordering on sarcasm; if you can advise better then do so but don’t give it with the sarcasm; I just hope you need some advise in the area’s I really do know about; you wanher!
John; Now I’m angry 
Due to the helpful comments of our previously SILENT friend, I felt the need to go & conduct some “live” tests in my own shower system ;
Gravity, no pump = 2 litres/min
Pumped (2.2 bar) = 8 lites/min
(on that basis, I'm not quiet sure how you would achive a minimum 10 litres/min minimum?)
In spite of installing many pumped shower systems, I will confess that I’ve only ever done flow tests on the gravity feed before proceeding with a pump installation to see exactly what I’m dealing with. Looking at what comes out afterwards is usually more than enough to satisfy both me & the customer; but I’ve never actually done a pumped flow test on any of the systems I’ve installed.
I have 2 x 8” drencher heads & the pumped flow is more than enough unless you really want to drill holes in your head & shoulders! I will confess at being a little & surprised at getting just 8 litres/min when with the pump running but that may well be due to the size of the water jets; I though it would be more & perhaps I should get a bigger shower head!
So, on that basis, I stand by my original advise that 5 litre/min would be acceptable, 3 litres disappointing;
ANY COMMENT TO ADD MR SIMOND!
Due to the helpful comments of our previously SILENT friend, I felt the need to go & conduct some “live” tests in my own shower system ;
Gravity, no pump = 2 litres/min
Pumped (2.2 bar) = 8 lites/min
(on that basis, I'm not quiet sure how you would achive a minimum 10 litres/min minimum?)
In spite of installing many pumped shower systems, I will confess that I’ve only ever done flow tests on the gravity feed before proceeding with a pump installation to see exactly what I’m dealing with. Looking at what comes out afterwards is usually more than enough to satisfy both me & the customer; but I’ve never actually done a pumped flow test on any of the systems I’ve installed.
I have 2 x 8” drencher heads & the pumped flow is more than enough unless you really want to drill holes in your head & shoulders! I will confess at being a little & surprised at getting just 8 litres/min when with the pump running but that may well be due to the size of the water jets; I though it would be more & perhaps I should get a bigger shower head!
So, on that basis, I stand by my original advise that 5 litre/min would be acceptable, 3 litres disappointing;
ANY COMMENT TO ADD MR SIMOND!
Maybe Mr Simond is in hiding but thescruff isn't.
The question is un-answerable, so lets not assume or guess.
The manufacturer will publish minimum flow rates, and that will depend on the size of the holes as much as the size of the rose.
Simple ain't it Simon, 5ltrs/m will be ok for one 200mm rose but not another, which one do you have
but thescruff isn't.The question is un-answerable, so lets not assume or guess.
The manufacturer will publish minimum flow rates, and that will depend on the size of the holes as much as the size of the rose.
Simple ain't it Simon, 5ltrs/m will be ok for one 200mm rose but not another, which one do you have
Well maybe, we’ll see!Maybe Mr Simond is in hiding
Well you got me there; Who TFIH?
Practical test is as good as you will get so I didn't assume or guess, I actually measured it; so does that not answer the question!
Granted but I don’t think they are that much different, like for like.
I really haven’t got a clue what I have here; but, like all the systems I install, I get as good & as I can for the customer at the best price I can unless there is a customer preference.Simple ain't it Simon, 5ltrs/m will be ok for one 200mm rose but not another, which one do you have
FFS it’s only holes in chrome plate with a bit of rubber around them & even rubber jets can be at the high end! The flow requirement is dependant on the number & size of holes & it doesn’t make much difference on the majority of 200mm heads unless you’re looking for 2mm+ jets which maybe only the most expensive (by name) may have; but then your going to need a top end pump anyway! Unless your at the really serious end or the food chain, they are all very similar & are all “much of a much ness”, otherwise they would not be saleable!
So are you Mr simple, Mr simon or, God forbid, Mr simond?
Edit; Sorry B&Q, having read that again, even I have to larf at it
Practical test, you actually measured it. 
You have the same Rose as John then, or did you assume they was all the same.
The size and number of holes could make as much as 50 ltrs/min difference, I fitted a 600mm rose in London that uses 67 ltrs/min, fed from a 28mm pipe, to say they would be disappointed with 5 ltrs/min is an understatement of the year.
" Doesn't make much difference between 200mm roses"
Only about 700% between the lowest and highest
You have the same Rose as John then, or did you assume they was all the same.
The size and number of holes could make as much as 50 ltrs/min difference, I fitted a 600mm rose in London that uses 67 ltrs/min, fed from a 28mm pipe, to say they would be disappointed with 5 ltrs/min is an understatement of the year.
" Doesn't make much difference between 200mm roses"
Only about 700% between the lowest and highest
I'm not hiding, I just don't look at this site all day.
A basic shower rose on a pump can be considered to give a worthwhile shower at around 12 litres per minute. As DIA says, a 'drench' head could run at 15 litres to pretty much any flow rate - 30 litres per min is not uncommon.
An instantaneous electric shower such as an £80 Gainsborough 8.5Kw can deliver around 3 litres per minute, depending on temperature in/out.
Customers wanting drench heads of up to 200mm on pumped/unvented should be assumed to be desiring 15l/m upwards.
If you deliver a 5 litre shower in this scenario you will probably end up at trading standards. You might have well have saved their money and fitted a Gainsborough cheapy, and they could danced around to get wet underneath.
A basic shower rose on a pump can be considered to give a worthwhile shower at around 12 litres per minute. As DIA says, a 'drench' head could run at 15 litres to pretty much any flow rate - 30 litres per min is not uncommon.
An instantaneous electric shower such as an £80 Gainsborough 8.5Kw can deliver around 3 litres per minute, depending on temperature in/out.
Customers wanting drench heads of up to 200mm on pumped/unvented should be assumed to be desiring 15l/m upwards.
If you deliver a 5 litre shower in this scenario you will probably end up at trading standards. You might have well have saved their money and fitted a Gainsborough cheapy, and they could danced around to get wet underneath.
I measured flow at the kitchen sink and got approx 10 litres/min from the hot tap, about 12 l/m from hot and cold together (it is a combi so mains pressure but I am not equipped to measure the pressure)
sounds like it might not be enough
Don't know why people are getting irascible.
sounds like it might not be enough
Don't know why people are getting irascible.
DIYnot Local
Staff member
If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Are you a trade or supplier? You can create your listing free at DIYnot Local