) the total head pressure (and hence total flow rate) should simply increase
In theory (yeah, I know
and that's it.
However, what can happen if you hit the right frequency combination is that their combined sound
becomes rather unpleasant since you can get a beat (Wikipedia).
It shouldn't be a huge problem if you can adjust at least one of the pumps, you'd just need to change
the frequency of the variable pump very slightly since they really do need to be quite accurately
matched to each other for this phenomenon to be noticeable (especially if you've decoupled them
properly).
I'd say try it out, especially since you already have the pumps.
EDIT: Here's quite an extensive article on multiple pump setups, in which Martin mentions
this phenomenon as well IIRC (it's been a while since I've read it), although I don't think he calls it by
name.
I might be in this boat purely by accident.
I broke the adjustment stick on one of my D5 varios, so it *might* not be running full steam like it's supposed to be. No issues yet, as far as I can tell, but I might only have one pump running at 4 - 4.5 instead of 5, so I wouldn't expect that to cause issues.
In theory (yeah, I know
and that's it.
However, what can happen if you hit the right frequency combination is that their combined sound
becomes rather unpleasant since you can get a beat (Wikipedia).
It shouldn't be a huge problem if you can adjust at least one of the pumps, you'd just need to change
the frequency of the variable pump very slightly since they really do need to be quite accurately
matched to each other for this phenomenon to be noticeable (especially if you've decoupled them
properly).
I'd say try it out, especially since you already have the pumps.
EDIT: Here's quite an extensive article on multiple pump setups, in which Martin mentions
this phenomenon as well IIRC (it's been a while since I've read it), although I don't think he calls it by
name.
