mega flow 250dd he

[Tony6]

Does anyone know how far the draw offs can be from an unvented cylinder.I have phoned the tech department but they dont know?

Specificatons 250 litres ,2 x 3kw recovery 119 min

Thanks tony........

 

[oilman]

Well, how long's a piece of pipe? You can have it a very long way away, but it will take a long time for the hot water to come through, unless you heat the pipe.

 

[Tony6]

i take it you dont know the calculation

 

[croydoncorgi]

If the distance is too great, and the water (inevitably) takes a lomng time to run hot, you'll need to make it a circulating system, with a low-capacity pump pulling enough water back to the cylinder to keep the pipes hot. And of course you'll need to insulate all the HW pipes, otherwise you'll burn lots of extra gas due to heat loss

 

[oilman]

i take it you dont know the calculation

This is life, not a maths paper. If you would like to put a few conditions in, then you can calculate. My statement was a correct answer to your question "How far can the draw offs be from an unvented cylinder?" AS FAR AS YOU LIKE, but you will have waiting time and temperature loss to deal with.

This is similar to the stupid calculations done to size a boiler, which for a medium to large house may be 30kW to 40kW. Then they go and stuff it all by putting in 22mm pipes.

You define:
how long you want to wait for hot water to come out of your pipe,
how near the temperature of the tank you want it,
how many bends you have in the pipework,
what is the flow rate from your water supply,
and any other points you consider relevant to your lifestyle

then we can tell you the distance.

 

[Tony6]

Oilman,
you are quite right in your reply regarding change it all and use 22mm pipes

As i have just become quialified in installing unvented cylinders .The one i hav`nt learnt is, if the length of runs to the appliances make any difference, Apart from using comon sense.

I was trying to find out the best location to site the cylinder to reduced cold legs. If there was a calculation then i could try and centre the cylinder.
At the moment the cylinder is sited in a basement on the design plan to serve a basement sink and washing machine about 2m away,a kichen sink on the ground floor about 7m away,fist floor bathroom ,bath,shower and basin about 12m away ,and a second floor on-suite basin and shower 14m away.

If the cylinder will operate at 3 bar pressure {hot water} then i will have no problems on deliverying water {flow rate} but it might not be cost effective to wait for the hot water ?

This is what im trying to find out? I dont want to install a system only to find out the hot water draw offs take a while to get hot...........

 

[IanDB]

Tony. just a complete amateur but ..... 1m of 15mm pipe holds 1.7lt of water so if your tank is 14m away from the second bathroom you'll have to run off 23lt of water (3 watering can fulls in my book) before getting the hot water through. (Feel free to check my maths on that one!! )

Ian.