taco 007?

[bschwartz]

I am currently using a taco 006 pump for the primary cooling loop on my 6/1.  I will be adding a secondary loop with a FPHE to heat my house ( well a room anyway).  I have a spare taco 007 laying around.

The quesions are:
Will this 007 pump be too big?
If it is too high a volume, can I put a ball valve inline to restrict the flow without hurting the pump?

[squarebob]

A ball valve after the pump will not be a problem. Here is the flow chart for all the little tacos.

Bob

[rl71459]

Keep an eye on that "007".

They are known for risky behavior! Driving Highly modified sports cars at high speed's, Frequently firing high power weapons, And sleeping around with loose women.

Sorry, I tried to resist but gave in to temptation.
Rob

[bschwartz]

Nice Rob 
Don't bother trying to resist the temptation..... it's not worth the effort

Taco gets the valve then.

Thanks Bob.

[cognos]

In general, you can throttle the outlet of a centrifugal pump. Try to stay within the ratings - watch the pressure and flow rates, make sure that you stay on the curve.

Don't throttle anything positive displacement... you get pieces of pumps, and zero flow...

[bschwartz]

         "Try to stay within the ratings - watch the pressure and flow rates, make sure that you stay on the curve."


How do I do that?

[squarebob]

I am wondering if a thermostat with a small bleed hole on the outlet of the "domestic" side of the heatex would give the flow control and temp control you are looking for in the in-home radiator?

Bob

[bschwartz]

Temp control isn't really a big issue.  I'll probably just have a remote on/off for the domestic circulator pump.  My concern is having too much flow which won't allow enough delta to transfer heat well.  I also don't want to throttle the pump so much in order to get a good delta, that I cause a problem with the pump. 

I'd think the thermostat would simply prevent the system from circulating until up to temperature.

I'm actually hoping there may a small amount of thermosiphon taking place even with the system (engine) off.
If a small amount of heat gets sucked up by the radiator in the house and causes gentle flow, I may be able to get away without running antifreeze in the domestic loop.  The workshop where the engine is located is insulated well enough that even in winter, it never gets below freezing.  The loop will be run in copper through the wall from the workshop, outside, then underground about 12" then up and into the house.  The house and workshop are about 15' apart.  Lines will be covered in black slip on foam insulation.

As I live in Southern New Mexico, nightime temps in the coldest of winter are in the 20's. 
Thoughts, ideas, suggestions???

[cognos]

Centrifugal pumps are happiest when they are matched in both discharge pressure and flow rate to their expected service. This is done with impeller and volute design. Some are designed to work across a range of pressures and flow rates.

Staying within the curve - you'll need to be able to measure the discharge pressure at the pump, and you'll need to be able to measure flow after your throttle valve and load flow restrictions (your required load flow).

Closing in the throttle valve *should* cause the discharge pressure at the pump to rise. It should also cut back on the flow.

Use the throttle valve to get your flow where you want it. Measure your flow. You can run it into a 5 gallon bucket (on the outlet of your load, the return line, preferably), measure the time it takes to fill, divide/multiply etc. until you get a gallons/minute figure you can use... see where this figure comes up on the pump performance chart, and see what pressure range is acceptable for the pump at this flow rate. If you are within the pressure range for the flow you have, you are good to go. If you are under the recommended pressure at the required flow rate, your pump is undersized. If over, you will have to change something in the name of pump longevity/reliability.
In my experience - the problem I see most often is that the flow is too low for the pressure (ie. pump discharge is throttled in, too far closed). The solution for this is a bypass line from the pump discharge back to the suction line, this line can be throttled to increase the flow and decrease the pressure on the pump. Then you will need to adjust your required load flow again, and do the whole process over again until you have "balanced" the system.
A change on either throttle valve will affect the whole system.

If you find that the throttle valve on the pump is wide open, and the pressure is still too high, but you aren't getting the required flow, you will need to decrease flow restrictions in your load - or get a different pump.

If you find that with the discharge throttle valve wide open, the discharge pressure is too low and you don't have the required load flow, your pump capacity is too low.

Just a quick overview of pump sizing. It make more difference in larger pumps. But a throttled-in pump running outside it's designed performance curve will have a shorter life than one in proper balance.

[bschwartz]

Okee Dokee.  That makes sense.  Return loop with a second ball valve it is then.  That way no matter how slow I want the flow, it won't hurt the pump.

[Ronmar]

A bypass or recirc line with a valve in parallel with the pump is how I throttle my small Taco circ pump.  you can just see it in my avitar.  I use this in conjunction with the thermostat on the outlet of the heat exchanger to provide for a more consistent flow at the thermostat's operating temperature.  Without the bypass line, it will surge a bit, particularly when the water feeding the heatex is cold, as the unthrottled pump flow forces too much water into the heatex too fast to be heated to the thermostat temp...  With the valve properly throttled, I get a steady output of 120F water, that flows at a rate based on the engines load.  I get around 1/4 GPM at 1KW of electric load on the generator, up to around 3/4 GPM at 3KW of electrical load, starting with around 60F water if I recall my numbers correctly:).

[bschwartz]

Ronmar,

Looking at your avatar, it shows that your main coolant goes through a heat exchanger.  What happens if your secondary loop stops for some reason?  Do you have another system in place to draw off excess engine heat?

[Ronmar]

Ronmar,

Looking at your avatar, it shows that your main coolant goes through a heat exchanger.  What happens if your secondary loop stops for some reason?  Do you have another system in place to draw off excess engine heat?

What happens?  Well it overheats of course:)  No alternate cooling system/radiator, it all goes into the heatex and secondary loop.  Here is where an overtemp switch on the side of the head comes into play, just in case...

[billswan]

Ronmar,

Looking at your avatar, it shows that your main coolant goes through a heat exchanger.  What happens if your secondary loop stops for some reason?  Do you have another system in place to draw off excess engine heat?

What happens?  Well it overheats of course:)  No alternate cooling system/radiator, it all goes into the heatex and secondary loop.  Here is where an overtemp switch on the side of the head comes into play, just in case...

Guys on my secondary loop I have a flow sensor that senses flow. If the secondary loop stops the sensor breaks a circuit and a murphy switch shuts down my listeroid. The switch is some thing meant for boat engines coolant flow. Found it on ebay.............

Billswan

[lowspeedlife]

Ronmar,

Looking at your avatar, it shows that your main coolant goes through a heat exchanger.  What happens if your secondary loop stops for some reason?  Do you have another system in place to draw off excess engine heat?

What happens?  Well it overheats of course:)  No alternate cooling system/radiator, it all goes into the heatex and secondary loop.  Here is where an overtemp switch on the side of the head comes into play, just in case...

Guys on my secondary loop I have a flow sensor that senses flow. If the secondary loop stops the sensor breaks a circuit and a murphy switch shuts down my listeroid. The switch is some thing meant for boat engines coolant flow. Found it on ebay.............

Billswan

Hey Bill, got a link to the mfg of the flow switch your are using  ?


Scott R.