12 volt solenoid valves (again)

[CampinGazz]

my motorhomes central heating and hot water system can't be done how i had hopes... with 2 pumps as the pump must be before the boiler not after it,

So i'm back to needing valves again,

There must be somewhere i can get a couple of solenoid valves from cheaply, all places i've tried want 50 to 100 quid each!!

They need to have 12 volt DC coils, able to take 85 degree C water mixed with vehicle antifreeze, flow 15 litres per minute, and able to operate continuosely, i can put strainers in line to avoid anything contaminating an assisted lift diaphram,

i just need to source some cheap solenoid valves that do this, or any 12 volt DC valve that can shut off water flow and open it according to wether a

12 volt DC signal is present or not.

[The3rd Earl Of Derby]

Never realy looked at the voltage? but if they are 12v could be 24v though...washing machine H/C inlet valves?

[Andy Hall]

Why can't you have two pumps, in effect on the return circuits and with a branch on the flow side of the boiler?

[Sparks]

Would this work?

____>___>___>____RADS_____>____>_______PUMP1__>__ | | | | |___>__HOT WATER___>___PUMP2__>__| | _

[CampinGazz]

had to rule out washing machine valves, they are too small bored for this system which needs to flow upto 900 litres an hour or it throws a wobbely and shuts down.

also i've been told the coils are only rated for intermitant use with hot water,

[CampinGazz]

Not sure to be honnest, i'm worried about the water being pushed around both systems by the one pump, they are basic centrafugal pumps, so offer no restriction or owt when not running.

I guess experementation would be called for, but i only have 2 weeks untill i'm due to use the van,

but you've given me another method to think about.

[Terry]

Here we use 115 volt 60 Hertz AC cold and hot water inlet valves on our clothes and dish washers. They never seeem to go wrong in my expereience. I've got a couple out of scrapped machines somewhere; when I'm downstairs tomorrow working on my clothes washer that won't pump out I'll try them on

12 volt DC. You never know. Now I'm curious!

[Andy Hall]

This was my suggestion as well.

The flows would depend on the relative resistance through the boiler vs. the circuits. Possibly the resistance through the HW arrangement would be comparable to the boiler, so that could be an issue with the heating circuit - i.e. some water flowing in a loop not including the boiler.

However, that is easily fixed with swing check valves of the type used in gravity CH systems to prevent gravity flow around the radiator circuit when the pump isn't running.

Look at

catalogue number 7463

Two of these and two pumps and I think you have a solution.

[Donwill]

"> i just need to source some cheap solenoid valves that do this, or any 12

Try gardening sources, they use 12volts solenoids for watering, maybe ask on a gardening news group? just a suggestion. Cheers Donwill

[Donwill]

">

What about these? Any good?

[Sponix]

A few 12v solenoid valves: rswww.com, for example: 440-789

If the bore diameter is too small presumably you could use two in parallel.

sponix

[Donwill]

VALVE 1

Assuming the*coils* from the 2 types of valves are interchangeable, the second valve i.e The hotpoint! the body (mechanical bits) is suitable for hot water. The coil from the first valve is rated at 24 volts but seller says it will run on 12volts, maybe continuously??

Possibly they are cheap enough to experiment with? maybe you can get similar valves from another source? Donwill

[CampinGazz]

Cheers for the replies.

Hopefully i have finaly sorted it out,

Found a twin output solenoid controlled valve from a merc car with climate control, single 3/4 hose in, 2 x 3/4 hoses out, normaly open, apply 12 volts to one coil and it closes, apply 12 volts to the other coil and it closes, it's supposed to recieve a PWM signal to vary the ammount the valve closes to regulate the water through put and hence the temp to the heater, but i dont need that bit, just open or closed,

and as they are normaly open i have the fail safe system i wanted, and i know for sure the valves can take the antifreeze mixture i'll be running at the temps the boiler runs at,

So maybe i have finaly cracked this, when the valve arrives i'll soon find out i guess.

[John Stumbles]

If you mean in the return rather than the flow then you should still be able to use a pump-plan system (as it's sometimes known, a la S-plan, Y-plan etc)

---------- flow | |--->>----------------------- | | | | | | PUMP 1 (V) PUMP 2 (V) | BOILER | | | | | LOAD 1 ~ LOAD 2 ~ | | | | | |-------------------------- | | | | | | LOAD 1 ~ LOAD 2 ~ | BOILER | | | | | PUMP 1 (V) PUMP 2 (V) | | | | | |---

[John Stumbles]

Alternatively some types of spring-loaded single check valves can be dismantled and the springs removed to give a low-resistance check valve. There are some sold for use between a shower house and mixer outlet which have 1/2" BSP male thread one end, female other, about an inch long, which may be worth looking at.

[fred]

In article , CampinGazz writes

That solution is a proprietary one which may cause you problems with maintenance. The alternative with 2 pumps and 2 low cost non-return valves in one where you will be able to source low-cost spares for some considerable time and one which should perhaps be preferred, I think it will work.

HTH ps: Thx to AG for the Ultraheat supplier, my newsreader missed your earlier reply.

[Roly]

My first thought was washing machine hot water inlet valves, but I can understand why they're unsuitable.

What about standard central heating motorised valves, but powered by a cheap 12 to 240V invertor ? You could use 12 V double pole relays to power the respective valve and energise the invertor only when one of the valves needs to be on.

[Sponix]

It'd be worth finding out the actual part number of the valve you have, and writing it down somewhere.

That way, when it inevitably goes wrong, you'll be able to get a replacement easily.

A quick email to one of the following should provide you with the Mercedes part number:

sponix

[CampinGazz]

yup, got the part number of the valve, and being a merc part i should be able to get a spare one anywhere in europe, like any parts for the eberspacher i have now, and i'll not have the fun i had last year of trying to find a part for a UK supplied only water heater in germany,

as the valves are normaly open if they fail it wont be the end of the world tho, i'll just have to manualy shut the rads down to turn the heating off if the valve goes in summer,

But the valve is for one of the high end merc convertables apparantly amoungst other models, so hopefully it'll be a part that lasts, especialy as i'll be using it only to either shut off or leave open the flow, where as in the car it's fed with a pwm signal below full open to make it chatter up and down to regulate the opening.