Is my water pressure calculation ok?

[Krug]

Hi, I used the kitchen scales and the open ended shower hose. Opened the cold tap and pushed the hose onto the scales until the water was almost stopped.

The scales read over 10 pounds, water was still spraying out of the sides. The area of the hose was approximately 0.12 square inches, so PSI was around 83 PSI, this works out to around 5 bar.

I do get water hammer sounds regularly. So can I safely assume my cold mains pressure is over 5 Bar?

Thanks

 

[Softus]

My hovercraft is full of eels.

 

[mogget]

Hi, I used the kitchen scales and the open ended shower hose. Opened the cold tap and pushed the hose onto the scales until the water was almost stopped.

The scales read over 10 pounds, water was still spraying out of the sides. The area of the hose was approximately 0.12 square inches, so PSI was around 83 PSI, this works out to around 5 bar.

I do get water hammer sounds regularly. So can I safely assume my cold mains pressure is over 5 Bar?

Thanks

I suspect that using a pressure gauge would be easier, less messy, and have an infinitely greater chance of being accurate

Don't give up the day job.

 

[hav it]

omg this has got to be a joke.( passes more towels)

 

[gremlin16]

So can I safely assume my cold mains pressure is over 5 Bar?

Only if your scales are calibrated

 

[mogget]

So can I safely assume my cold mains pressure is over 5 Bar?

Only if your scales are calibrated

There's an easy way to check!

Just put a jet in the end of the hose, aim it skyward and measure the height of the fountain that results

Make sure you've got the relevant training for your scaffold tower though, if you haven't, you might need to hire a helicopter.

 

[Krug]

No, it was a serious post. I want to install a combi boiler and want to know if I have enough water pressure for a good hot shower from it.

The boiler recommends a minimum of 1.9 bar for maximum temp rise output.

Where do I get a pressure guage for a tap from? How will I know if it fits my tap even? Are they expensive? I will be using it just the once, and I only want to know if the pressure os over 1.9 bar. In summer I notice the pressure is lower than winter.

6 lbs was not enough to come near stopping the flow of water.

 

[gremlin16]

A good installer will have the correct equipment to test your water pressure and flow rates.

 

[mogget]

No, it was a serious post. I want to install a combi boiler and want to know if I have enough water pressure for a good hot shower from it.

OK, serious answer.

If you've got an outside tap, or any other tap with a threaded outlet, you can do a simple test. Buy an adaptor, or adaptors so that you have a 3/4 inch socket on one end, and a 1/2 inch male thread on the other (a 15mm compression with the nut and olive removed will do for this purpose).

Screw the socket onto the tap, and your shower hose on to the other end of the adaptor. And also your showerhead on the other end.

Turn on the tap and you can see what the pressure's like, and also the flow rate if you like by timing how long it takes to fill a known volume (e.g a gallon bucket), and doing the maths to get litres per minute.

You can then pass this information to your installer who will be able to make sure you get the right boiler for the job.

 

[gremlin16]

You can then pass this information to your installer who will be able to make sure you get the right boiler for the job.

The installer should do the flow/pressure checks. If he cant, then hes a waste of space.

I for one would not take the word of a customer when he says "I have that much pressure and my bucket took that long to fill"
(probably die laughing)

Imagine what would happen if the installed boiler did not provide enough hot water, the customer would throw it back at you, because you should have done your own calcs.

How would you get out of that one

 

[mogget]

I did not say that the installer should take it on trust - it would be silly to do so.

The OP however is obviously feeling a bit 'handy' and I assume he wants to satisfy his curiosity. Hence I gave a description of a quick lash-up which will give him some idea of what to expect.

I do not expect him do do the installers job, and certainly not with a hose and scales!

 

[Softus]

Turn on the tap and you can see what the pressure's like

This is just claptrap.

Did you learn about plumbing from a Ladybird book?

 

[mogget]

Have you been referring to your copy of 'how to be patronising for dummies'?

Please, if I am wrong about something, please tell me why. That way I can learn, and so can others who may read the thread.

 

[Softus]

OK - try this for size:-

...timing how long it takes to fill a known volume (e.g a gallon bucket), and doing the maths to get litres per minute.

You can then pass this information to your installer who will be able to make sure you get the right boiler for the job.

Oh per-lease.

Have you ever, or do you know anyone who has ever, passed this kind of information to an installer, and found that the installer has relied on the information and proceeded with the work?

 

[mogget]

Thankyou.

No, I don't, and in retrospect it was a pretty dumb thing to suggest.

I do however think that as a 'quick and dirty' test to confirm that the mains supply is sufficient it is worth doing, from a DIYers point of view.

In fact, I wish I'd done the same myself before my combi was installed some years ago. It was so dismal that I ended up going back to a tank and cylinder.

You live and learn I guess.