How to determine the size needed of an electric unvented water heater to supply two ensuites

[dillonheger]

I have a Glow worm betacom 30c combi boiler that is not connected to any water tank/cylinder in a 4 bedroom 1 bathroom house. I am adding two en-suite bathrooms which will include a shower, basin and toilet in each (saniflo systems in each). I need to identify how to determine what size unvented water heater I need to install to supply both en-suites independantly of the combi boiler as the hot water pressure is an issue. Cold water pressure is fine though. I have been advised a 50L will suffice to support two ppl showering at the same time however is this true? The new en-suites will located on the ground & first floor, and I intend to install the water heater in the kitchen on the ground floor. Below is the water heater I am looking to purchase. Will this suffice to supply enough hot water to both en-suites as well as ensure no issues with pressure (in getting the hot water to the 1st floor en-suite)

Hyco Powerflow 3KW Unvented Water Heaters | Water Heaters

 

[ShaunCorbs]

Nope way off

Let's start at the beginning

What's your pressure and flow of your cold water coming in

Can test by using an outside tap or a normal tap

You might be best getting a plumber to check if you haven't got a gauge and go though the options

You will need static pressure (with no outlets open but the one with your gauge on)

Dynamic (one outlet open e.g. Kitchen sink as well as the guage on the outside tap)

And then flow rate which is easiest just time how long to fill a 1 litre container

 

[dillonheger]

Nope way off

Let's start at the beginning

What's your pressure and flow of your cold water coming in

Can test by using an outside tap or a normal tap

You might be best getting a plumber to check if you haven't got a gauge and go though the options

You will need static pressure (with no outlets open but the one with your gauge on)

Dynamic (one outlet open e.g. Kitchen sink as well as the guage on the outside tap)

And then flow rate which is easiest just time how long to fill a 1 litre container

Thanks for your response, I am unable to measure the flow rate right now but I believe the cold water pressure and flow rate is quite good. Once I do measure the flow rate then how do I determine what size water tank I will require for 2 ensuites?

 

[ShaunCorbs]

It all depends on your pressure and flow

Can't give good advice without knowing these

 

[dillonheger]

It all depends on your pressure and flow

Can't give good advice without knowing these

Ok just measured it. The flow rate is 5 secs to fill up a 1 ltr container.

 

[ShaunCorbs]

12lpm give or take no way you could have more than one outlet/ shower on at the same time and really not good enough for an unvented heater / cylinder

Your only way now would be a gravity system with a pump

Unless you want to go down the road of seeing if a water main replacement could give you better flow rate

 

[dillonheger]

Ok thanks. What other suggestion would you advise of if the water heater was not a suitable solution and I was unable to get the water main replacement improving the flow rate?

 

[ShaunCorbs]

Gravity fed hot water cylinder and 50-60 gallon plastic tank and a pump then you could run two showers at once

If you have the space

 

[dillonheger]

Gravity fed hot water cylinder and 50-60 gallon plastic tank and a pump then you could run two showers at once

If you have the space

Great thanks for all your help