Do I need a bigger pump?

[troubleatmill]

Hi all, wondered if you could help.

I'm at the 'filling the solar loop' stage of a set up - and having a few "issues".  I've got an Ecocirc4, and I'm wondering if it's got enough clout for the job  - wondered if you can advise. I'm not getting any change in the temperature of the sensors when firing up the pump using the TDC3 - got one tube in place as a tester.

So..the system

The panels are south facing, wall mounted, with 17m of 15mm pipe run to the cylinder (each way - so 34m in total) - 10 corners, two check valves, 18 L expansion vessel (with safety valve and fill loop).

The order is :

Panel - radiator style air vent on corner - down 4m to top of cylinder coil -through coil to return - expansion vessel - pump - gate valve - extra fill loop/drain - non return gate valve -  back to far end of panel.

Panel holds pressure at 1bar, but pump sounds a little 'bubbly' when trying to pump. I've pumped antifreeze round it from the extra fill loop, and loosened the fitting on the panel side of the pump (just before the non return valve) with no obvious spluttering. I've fitted the pump horizontally with the body below the pipework, but the body juts out from the wall at an angle of about 45deg so I can see the led.

The vertical distance from pump to manifold is 4m. From the vertical height it looks like the ecocirc 4 might be underspec from its head vs flow profile, but think it's OK from dynamic head only using the spreadsheet on here?


 I can't seem to find consensus on the whole static vs dynamic head conundrum - if head wasn't important at all, why do they quote it? Or are you supposed to convert it into dynamic head equivalent?  However I've read about someone pumping up 3.4m in a closed loop with a nominal static head quoted of 1.7m.

Am I at the limit of what this pump can achieve?  Or is there just still air trapped in the system and an unprimed pump?

Thinking about the grundfos ups 25-60 which claims a head of 7m - any thoughts?

Thanks in advance -

[micko]

I am using the same pump as you and mine is whisper quiet, the only way I can tell it’s on is by the led. If the pump is making noise I would suspect you still have air in your system.

[desperate]

My guess is that it is air causing your problems. You don't need to worry about the static or dynamic head, or any vertical distances from pump to manifold. Although it may be 4m from pump to manifold it is also 4m back down so the overall is zero. The pressure created by the pump just has to overcome the various resistances in the system provided it is bled of all air. The problems come about when air upsets that zero balance, if for instance the return from the panel to the pump is full of air, then your pump will have to lift a column of water against gravity as well as overcome the system resistance. The other problem that occurs frequently is when a big bubble replaces the water in the pump so stopping the pump working, sometime known as airlocked.

Your pump should easily have enough whoomph to overcome the resistance when the system is properly bled, one good trick is to switch the pump on and off, say 2 secs on and then 2 secs off repeatedly, this has the effect of rocking the airlock and sometimes gets things moving. It can be a frustrating timewaster trying to work out what is going on in there, look for places where air will naturally tend to collect, could you put an air bleed in the pipework in such locations?

One further thought, usually pumps ought to be fitted with the spindle horizontally to prevent end loading, they are not normally designed to handle any other orientation, and ideally pumping water uphill.

Good luck

Desp

[Iain]

Hi
Don't know about the pump but I have found it well worth while fitting a small 90 deg valve to bypass the non return valve. It allows for quicker filling and venting and also usefull if you have to drain the system.
Like this
http://www.screwfix.com/p/pegler-t-ball-valve-15mm-blue/21860
I used the "Red" one as it is hot!

It helps to stop air getting trapped between the pump and non return valve. Just open the valve when filling and venting air or draining.
When draining it stops the dead leg between the non return valve and the collector.
Iain

[troubleatmill]

thanks for all your replies. I think I may have had an air lock between the EV and the pump - undid the connector to the pump - little/no water though pressure gauge said 1bar - so opened the safety valve on the EV (think that lets air in?) and it went quiet so that may have allowed water past the connector? - but may have over done it and let too much air in sigh. EV is fitted vessel uppermost because of space considerations. 

How would I know if I'd f**ked the bearings?  Would the LED light still come on (it's green, constant now).

Cheers

[Richard Owen]

I put a deaerator in my system. Something like this: http://www.altecnic.co.uk/Solar/Automatic-air-vents-deaerators.html

Not cheap but does the job.

[micko]

I would be surprised if your pump is shot. Keep playing with the system to get the air out.
I had problems with my system and ended up fitting two bleed points, I think I was getting a bubble of air on the top of the cylinder coil where it leaves the cylinder, I installed it with a flat pipe run at this point, in hindsight I should have put a slope on it.

Do not try to use a TDC3 with this type of pump.
The green light shows the pump is running check it is not getting hot very .

[troubleatmill]

Thanks for all your input - I've now got the system up and running (yay). We've got half a metre of snow on the roof - so I'm glad I went for wall mounting. 44 x 58mm tubes today has given 210L of 53 deg water... Looks like the pump is running OK, with some caveats. I replumbed the expansion vessel so the fittings are on the top (well, space constraints mean at 45 deg but still better than with the fittings on the bottom re airlocks.

I don't know if anyone else has used a expansion vessel with a pressure relief valve on it, which (they may all be like this?) can be turned (and a plunger raised) to allow water past it?

It's an Altecnic 18L with a 'quatro' 4 way adapter on top. It feels like turning the top of the prv is supposed to be a temporary purge and that the prv is designed to work without turning this - but my ecocirc doesn't want to pump unless I 'frig' the prv.  I think it's probably still residual air in the system, so I was going to run and purge till it works OK - is that the best option?

thanks in advance

[Antman]

I've fitted the pump horizontally with the body below the pipework, but the body juts out from the wall at an angle of about 45deg so I can see the led.

The circulator (pump) should be fitted with the shaft horizontal (some manufacturers allow slightly upwards slope) but never below centre. The reason is it knackers the bearings and also any leak runs straight into the electrics 

Antman

[derekmt]

The circulator (pump) should be fitted with the shaft horizontal (some manufacturers allow slightly upwards slope) but never below centre. The reason is it knackers the bearings and also any leak runs straight into the electrics 

Antman

Pump axial bearing loads are affected by the varying pressure between the front and back of the impeller. The killer is when pressure profile causes the bearings become unloaded axially and there is no radial loading. With no loading at at all  the balls in the bearing  stop rolling and skid.  Flat spots develop ,then accelerated wear = kaboom.
Mounting the motor shaft horizontallly ensures there is always radial loading.