Hot/Cold water flow rate.

[DEMPSEY1965]

Hi can anyone answer me a simplish question. Should the flow rates of both hot and cold stored water be equal? I have just measured the flow rates of my downstairs shower with no pump and there is a notable difference when I turn the valve from hot to cold, the cold running faster. Is this normal or do I have some restriction in the pipework?

Many thanks

DEMPSEY

 

[tamz]

It depends on what type of system you have and how it is set up.
If for eg you have a combi boiler it will have a flow restrictor fitted inside the boiler or the valve throttled back.

 

[leoaplumbinguk]

[h=3]Finding: The hot water flows faster than the cold water.[/h][h=3]Reason: The viscosity or (fluid friction) varies with the material and with the temperature. The higher the temperature the lower the viscosity. The hot water has a lower viscosity than the cold water. The viscosity directly impacts the rate that the liquid material will flow. For two containers with the same depth of liquid, the lower viscosity material (hot water) flows with a higher rate out the same size openings in the bottom.[/h]

 

[dancinplumba]

hot pipe feed probably has more resistance. has to come from hwc, pressure will be the same
imho

 

[DEMPSEY1965]

Hi

I have an indirect system (is that right?). Stored hot water in the airing cupboard and also cold water tank in loft. I am thinking the cold will be faster because the tank is higher up in the loft. The shower is fed from both of these tanks.

 

[dancinplumba]

probably.
your cold water tank supplies hot water tank so pressure is the same, your cold feed to shr comes direct from cold tank, less fitting/ less resistance,the hot water is pushed out of cylinder by water in your cold water tank and travels to shower thru more pipe and fitting hence more resistance.
Have you cleaned filters on pipes to shower if it has any ?

 

[DEMPSEY1965]

To be honest I have tried. I have a line filter but I can't undo the bloody brass nut, stuck solid!

 

[dancinplumba]

And the thermostatic valve will be throttling back the hot water even tho you have it turned to full
imo

 

[dancinplumba]

and you may live in hard water area, you could have scale build up in pipes and/or valve
imo

 

[DEMPSEY1965]

Yes all this sounds so true. I have a new pump coming this week so see if there is a restriction in the old one.

 

[dancinplumba]

Yes all this sounds so true. I have a new pump coming this week so see if there is a restriction in the old one.

no offence but you said no pump in first post ??

 

[DEMPSEY1965]

The pump is broken and switched off,was just measuring the flow before the new one arrived?