The saga of Mr 'two pumps' Gazz's motorhome CH system got me wondering: where do you get 12V or 24V DC circulating type pumps from, and a bnus question for 10: how much do they cost?
Alternatively is there a cheap (
Sorry, not been on here for a while, so many projects on the go at once on the motorhome.
The 12 volt circulation pumps i had were for eberspacher or webasto water heaters, one was a genuine eberspacher pump, quite small, pulls about 1.5 amps in use, flows 900 litres per hour, which is only 15 ltres a minute i rekon, it's a pulse drive magneticaly coupled motor, i.e. the impellor sits in a chamber that's 100% sealed from the electrical side, no pyhsical coupeling of the impellor to the motor, it's driven by a rotating a magnetic field, it's actually pretty noisey in operation, well for my use anyway as a hot water circulation pump located a foot under the bed to be used all night,
The second pump i had was a mercedes circulation pump, similar to the eberspacher one, but it's a standard brush motor directly driving the impellor, so there's a seal that could go one day, not sure of the power consumption, it's a bit quieter than the eberspacher one as it is smoother in operation. flow is about the same,
To buy them, the merc pumps can be had from a mec dealer, or from a scrap yard, they are fitted to most mercs and are used to keep the coolant flow high through the heater matrixes when the engines ideling, they are usually located near the front of the engine, follow the heater pipes and you'll find the pump if someone else hasnt already had it, silver motor, black head easy-ish to spot,
price for them i dunno, prolly £100 new on ebay, havent looked.
The eberspacher one, you can buy them from eberspacher or webasto heater dealers, but don't, as they'll charge the earth for it, look on ebay, ebay uk prolly sells them for daft money, but try ebay germany, as these heaters are much more common over there, and hence parts are much cheaper, (i bought an exhaust silencer for my heater off ebay germany for 18 quid after conversion and including postage to the uk which took 2 days, at the same time an identical silencer sold on ebay uk for almost 60 quid... likewise my heater cost me £315, brand new, over here they are a grand new)
Both webasto and eberspacher do water heaters, as do mikuni and some other diesel fired heater maker, boats use them a lot more than vehicles, but avoid a boat chandlers, the one in nottingham had a 24 volt circulation pump on it's shelf... price tag of £125, but all these heater's use a 12 or 24 volt circulation pump that is designed to handle boiling water,
I guess if your planning to run the pump for a long time, go for the eberspacher pump as opposed to the merc one, as the eberspacher dosent have a shaft seal to wear out and leak water into the windings.
I thought you might be out travelling in it!
It's for intermittent use: pumping primary water from a heat bank through a heat exchanger when there's a call for domestic hot water.
I had a look on ebay.de. There are Webasto Standheizungs e.g.
However the Merc one should do for proof of concept (if I can find a Merc in a breakers yard). Actually a gash low voltage shower pump might do at a pinch.
I could work on variable speed drive to a Grundfos-type mains pump if the 12V one it works as I hope.
Thanks for the pointers
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