Auxilliary water pump to improve flow through heater

[Bandit1200]

Good Evening
My Stag is fitted with a Davies Craig electric water pump and I intend to fit an auxiliary water pump to improve flow thro the heater matrix.
I've used the search facility but can find no reference to this subject.
Please could anyone with experience of such a modification kindly post photos, schematic diagram and or link to the post relating to the subject?
Thanks in advance
Steve

[jagorstag]

Moved from the Technical Guides section (which is not for posting technical queries) to make it visible to all members.

Cheers,
Joakim

[Matt Cook]

I have an electric water pump, I have the EJ Ward kit with the hose kit they do that plumbs the heater return into the pump suction. Heater works well, no need for an extra pump

Matt

[Stagdad]

As Matt says just plumb heater return and bypass return into the suck side of the new pump.

[dasadrew]

Just speculation here, but if the reason to want more flow through the heater is because it doesn't get warm, maybe it could be that the heater matrix is "crudded up"? Even with the 'feeble' original pump the heater gets hot enough (after I got rid of the collected sediment and 'crud' in the heater matrix).

Drew

[wader3]

I have the electric pump also with no issues. There was a couple of hoses to blank off as i remember from the original pump housing and thermostat to remove. Has that been done? As has been suggested it could be the heater matrix. I think the valve can get stuck on them too.

[Richard G]

I put an auxillary pump in for the heater but it does not make any difference. And I have a new Matrix in the heater.

[flying farmer]

If your thermostat has been removed as it says to do in the instructions, ignore them and refit the thermostat. An 82 degree thermostat will stay shut on a cold engine and force water through the heater, but will open before the electric pump moves out of cold running mode.
If your pump controller is the early type that pulses on and off heater output will still be dreadful unless a heater pump is fitted as the pump is only working 30% of the time.

I have 4 cars fitted with davies craig pumps and the only one with a crap heater had the controller fitted, all the rest have the pump running continuously at slow speed by dropping the voltage across a MK1 ignition ballast resistor. The only reason it had a controller fitted was because I bought the whole kit 2nd hand off ebay for just the price of a pump.
In the end I removed the controller on the one car with it fitted (my Rover V8 engined Toledo) and went the resistor route with that one too. I can now use the car in the winter, it was unuseable in frosty weather before that as the inside of the screen would freeze while driving!
Neil

[fussydave]

I have the Wards water pump with the hose kit and the problem with the heater still persists. The reason I believe is that the later pumps work by pulsing on and off for thirty seconds when the temperature is low and this means that there is an on and off flow of water through the heater thus the heater warms and then goes cool in pulses. In the cold weather my engine never gets above 70-75 degrees so the pump never gets into the constant running phase.

Dave

[Peter707R]

Agreed - the pulse is so infrequent that the heater goes cold in cold weather before the next pulse. I have fitted an auxiliary pump in the return from the heater to the electric pump input that is controlled by the heater fan switch. When the fan is turned on the pump operates. I had to fit a flow restrictive to the header tank lower/outlet otherwise I get water circulating through the header tank rather than simply providing a head if pressure. Tried other positions for the aux pump but had issues when using the heater temp control.

[Bandit1200]

Thanks all for your comments.
As my pump is situated at the bottom radiator pipe, there is no space to connect to the input without radical replumbing.
With the benefit of your suggestions I shall:
1. Re programme the digital controller to operate the pump more frequently and lower the temp at which the fan cuts in.
2. Ensure that the heater valve is fully open and matrix is clear.
3. Reinstall thermostat
4. Flush and replenish the system.
5. Fit a bleed valve to the pipe connecting the heads to ensure no air lock.
I'll report back on results.
Thanks again.
Steve

[Guerpillon]

Mine has a belt driven water pump, see picture. Very efficient, even during hot summer days. 3D7F1BEA-E4DD-4D82-92B6-30AC9C7977DD.jpeg

[Stagdad]

I In the cold weather my engine never gets above 70-75 degrees so the pump never gets into the constant running phase.

Dave

That doesn't sound good from an engine wear point of view.

[bullstarz]

I have fitted another heater in the rear of the car ,that uses an electric circulation pump to draw coolant through. With the roof down on a cold day you get a nice blast of warm air rolling around the car. It's also used to circulate coolant around the engine with the ignition off until the temp is below a set temp (85 deg C). The idea is to stop any localised boiling or potential warping.

[Bandit1200]

I've now drained and flushed the system. The water runs clear through the heater matrix and the valve is fully open. The pipe which runs from the water pump along the top of the RH head was connected to the upper matrix pipe so I've reversed the connections to the matrix. Also, following Neil's comments on the infrequent pulsing of the DC pump, I'll re programme the controller for more frequent pumping and follow his advice and refit the thermostat. Following DC fitting instructions, I blocked the U pipe connecting the thermostat housing with the original water pump housing. Should I unblock it or leave it blocked?
Key to success when refilling the system is avoidance of air locks. To this end I want to fit a bleed connector in the pipe which runs from the top matrix connector to the rear of the LH head but cannot find a supplier of a 12mm fitting. Any suggestions please?
Thanks
Steve