megaflo. No hot water unless 2 taps running

[jjmalc]

Hi,
Much as the post says. Had a megaflo for a couple of years with no probs. Very recently there was no hot water coming out the hot taps. We found that with another hot tap running somewhere there would be hot water coming out both with no probs. When you turn off one,the one remaining on would then run cold.
Any ideas? We are in a hard water area and a plumber is coming to have a look this pm.
Our water was cut off for a while last week for maintenance on the mains somewhere local. I`m thinking possibly the strainer is partially blocked?
Any advice most gratefully recieved
Cheers

 

[twgas]

do you have shower(s) connected to hot and cold supplies?

 

[jjmalc]

I have a shower which is a "aqualisa" and has hot and cold pipes into a mixer unit,which then outputs to the shower.
The shower is the only thing that will work fine with no other tap running.
Cheers

 

[twgas]

can you isolate the shower as I suspect cold is passing through shower into hot supply, there probably isnt enough let-by to keep 2 hot taps running cold.

 

[jjmalc]

Thanks. I`ll give that a go and let you know.

 

[BigBurner]

This needs a pressure equalizer as well. when pressures are equal on hot and cold one does not run into the other. They also stop scalding in the shower when a tap robs cold water away from the shower.

 

[jjmalc]

Thanks again folks.
Problem is not in the aualisa unit,but a shower mixer in the other bathroom which is letting cold into the hot.It`s now isolated and I`ll sort a new one out.
Very useful forum this and I will be using it again! (hopefully not too much,but I do not rate the plumber that Sunley Homes used for this one!)
Cheers

 

[DP]

The cold should be sourced from the cylinder. Looks like the installer took the easy way out and 'forgot' to provide balanced feeds.