Speed control of Central Heating Circulator

[Terminal Crazy]

Hi guys, title says it all really.

I want to control the speed of a central heating pump somewhere slower than
normal.

Q1. What sort of motor is in a domestic central heating pump (UK 50Hz
single phase ).

Q2. Is it controllable from an Inverter? These usually run shaded pole or
Capacitor run/start type motors.

Q3. Does anyone have any suitable circuit diagrams for a speed controller,
fixed speed would do. I'm guessing the speed is controlled by the
frequency.


TIA

 

[Rich Grise]

Hi guys, title says it all really.

I want to control the speed of a central heating pump somewhere slower
than normal.

Q1. What sort of motor is in a domestic central heating pump (UK 50Hz
single phase ).

Q2. Is it controllable from an Inverter? These usually run shaded pole or
Capacitor run/start type motors.

Q3. Does anyone have any suitable circuit diagrams for a speed controller,
fixed speed would do. I'm guessing the speed is controlled by the
frequency.

What is it you mean by "heating pump"? If it's a "heat pump" (i.e., a
reversible "air conditioner"), then the compressor motor shouldn't be
messed with, period. If you're simply talking about the blower that
circulates the air, then we'd need to know what kind of motor is driving
it. I guess it's kind of hard to control an induction motor that wasn't
designed for electronic speed control.

Good Luck!
Rich

 

[Terminal Crazy]

What is it you mean by "heating pump"? If it's a "heat pump" (i.e., a
reversible "air conditioner"), then the compressor motor shouldn't be
messed with, period. If you're simply talking about the blower that
circulates the air, then we'd need to know what kind of motor is driving
it. I guess it's kind of hard to control an induction motor that wasn't
designed for electronic speed control.

Cetral Heating Hot water circulator such as CirculatingPumps CP53
http://www.circulatingpumps.net/products/cprange.asp

The only info i have so far is it's a "drum motor design" whatever that
means. It does come with 3 selectable speeds similar to most domestic
pumps.



Thanks

 

[Rich Grise]

Cetral Heating Hot water circulator such as CirculatingPumps CP53
http://www.circulatingpumps.net/products/cprange.asp

The only info i have so far is it's a "drum motor design" whatever that
means. It does come with 3 selectable speeds similar to most domestic
pumps.

Ok, fair enough, but what is it you want to accomplish that it can't
already?

Thanks,
Rich

 

[Terminal Crazy]

Ok, fair enough, but what is it you want to accomplish that it can't
already?

I'd like to run it at a slower speed than it currently does.

I could throttle it back but that would be inneficient.

I have a large 200,000 BTU Oil fired boiler which heats the house. I have
also linked in a 30-40,000 BTU Multifuel stove heating the system. Just
using gravity circulation the boiler/pipework can get noisy/hot. with the
pump running it removes the water too fast. Very likely the pump is way too
big for the section it's serving.
Rather than replace the pump, I was wondering if I can control its speed.
Most inverters seem to do Capacitor run/start motors or shaded pole, but i
don't know what type of motor this uses.

Ideally, if I can control the speed, I can control the temperature of the
water circulation within limits.

Is it possible the speed can be reduced ?

Thanks

 

[Jamie]

I'd like to run it at a slower speed than it currently does.

I could throttle it back but that would be inneficient.

I have a large 200,000 BTU Oil fired boiler which heats the house. I have
also linked in a 30-40,000 BTU Multifuel stove heating the system. Just
using gravity circulation the boiler/pipework can get noisy/hot. with the
pump running it removes the water too fast. Very likely the pump is way too
big for the section it's serving.
Rather than replace the pump, I was wondering if I can control its speed.
Most inverters seem to do Capacitor run/start motors or shaded pole, but i
don't know what type of motor this uses.

Ideally, if I can control the speed, I can control the temperature of the
water circulation within limits.

Is it possible the speed can be reduced ?

Thanks

have you thought about using a zone valve? You can employ them to
do bypass of hot water delivery. They come in a variety of combinations
just depends on how you want to divert the water. Simply let the
water that isn't be used go back to the tank..

http://www.pexsupply.com/Zone-Valves-Controls-324000


Something to look at..

 

[Baron]

Terminal Crazy Inscribed thus:

I'd like to run it at a slower speed than it currently does.

I could throttle it back but that would be inneficient.

I have a large 200,000 BTU Oil fired boiler which heats the house. I
have also linked in a 30-40,000 BTU Multifuel stove heating the
system. Just using gravity circulation the boiler/pipework can get
noisy/hot. with the pump running it removes the water too fast. Very
likely the pump is way too big for the section it's serving.
Rather than replace the pump, I was wondering if I can control its
speed. Most inverters seem to do Capacitor run/start motors or shaded
pole, but i don't know what type of motor this uses.

Ideally, if I can control the speed, I can control the temperature of
the water circulation within limits.

Is it possible the speed can be reduced ?

Thanks

Why not just use a restrictor valve. Pump continues to run but the flow
is reduced.

 

[Jasen Betts]

Hi guys, title says it all really.

I want to control the speed of a central heating pump somewhere slower than
normal.

Q1. What sort of motor is in a domestic central heating pump (UK 50Hz
single phase ).

Probably a split phase induction motor (especially if quiet running)
there should be a "boilerplate" on it somewhere that says.

Q2. Is it controllable from an Inverter? These usually run shaded pole or
Capacitor run/start type motors.

Q3. Does anyone have any suitable circuit diagrams for a speed controller,
fixed speed would do. I'm guessing the speed is controlled by the
frequency.

assuming it's hydronic central heating and a centrifugal pump simply
reducing the voltage may be enough as the torque will reduce
proportionate to the speed, if it's a displacement pump trying that
may overheat the motor.

 

[Baron]

whit3rd Inscribed thus:

That raises the backpressure, could stall (and overheat) a pump motor.

The other way is to have a valved shunt, so the water flows in the
heating system and also through a second, parallel, loop (like
a short circuit). The pump still puts out the same number of
gallons per second, but the house pipes only see part of the flow.

I can see the advantages of that method.
I do use a restrictor valve on my system, but its only a two radiator
loop.

I did a quick test by closing the valve completely, the pump, at its
slowest setting still runs, but you are right it does labour somewhat.
I didn't run it like that long enough to see if it got too hot. Oddly
if I set it to the highest speed, it doesn't seem to labour at all.

 

[Rich Grise]

whit3rd Inscribed thus:

I did a quick test by closing the valve completely, the pump, at its
slowest setting still runs, but you are right it does labour somewhat.
I didn't run it like that long enough to see if it got too hot. Oddly
if I set it to the highest speed, it doesn't seem to labour at all.

Is it a centrifugal pump? In a vacuum cleaner, when you block the hose,
and it goes "Woooeeeee," speeding up, and it sounds like it's laboring
terribly, did you know that the current draw decreases? That's because
when a centrifugal pump isn't moving any fluid, there is no load, because
no work is done, so the motor speeds up because of the reduced load.

Cheers!
Rich

 

[Jamie]

Is it a centrifugal pump? In a vacuum cleaner, when you block the hose,
and it goes "Woooeeeee," speeding up, and it sounds like it's laboring
terribly, did you know that the current draw decreases? That's because
when a centrifugal pump isn't moving any fluid, there is no load, because
no work is done, so the motor speeds up because of the reduced load.

Cheers!
Rich

You most likely are talking about units that employ a universal motor..

They like to spin out of control when the load is removed but serve
as a great motor for vacuums..

I do think he is using a drum motor for that application.

 

[Baron]

Rich Grise Inscribed thus:

Is it a centrifugal pump? In a vacuum cleaner, when you block the
hose, and it goes "Woooeeeee," speeding up, and it sounds like it's
laboring terribly, did you know that the current draw decreases?
That's because when a centrifugal pump isn't moving any fluid, there
is no load, because no work is done, so the motor speeds up because of
the reduced load.

Cheers!
Rich

As far as I know it is a centrifugal pump. The inlet feeds the centre
of the impellor and the outlet is at the edge. Its also a capacitor
start/run motor with three speeds. I assume tapped windings.

 

[Rich Grise]

Rich Grise Inscribed thus:

As far as I know it is a centrifugal pump. The inlet feeds the centre
of the impellor and the outlet is at the edge. Its also a capacitor
start/run motor with three speeds. I assume tapped windings.

It'd be worth checking, because, as I said, a centrifugal pump wouldn't
be harmed by sticking a restrictor valve in the line, as someone else
suggested.

Cheers!
Rich

 

[Jasen Betts]

It'd be worth checking, because, as I said, a centrifugal pump wouldn't
be harmed by sticking a restrictor valve in the line, as someone else
suggested.

as long as you don't get cavitation it won't be harmed.

if it's tapped windings reducing the supply voltage is probably
harmless too.