Wilo Rs50 to Grundfos Alpha 2l problems!

[ianmcd]

FYI i rotated the head 180 degrees before fitting so the the plug was from the bottom as per the manual, flow is downward.
PRV setting anyone?

take a pic please of both sides of your pump and post it

 

[Patrick Hutchinson]

Done

 

[Patrick Hutchinson]

And?

 

[ianmcd]

Yes that is pumping the correct way, you would be surprised at the amount of people that think if you rotate the head that it changes the direction of flow, as said in the manus instructions that they dont like the pump to be on vertical pipe but cant see why yours being that way could cause your problems

 

[Patrick Hutchinson]

Actually the manual says the pipe work must be vertical with the shaft horizontal!

 

[ianmcd]

sorry you are correct I was reading that wrong there yes the shaft must be horizontal, you keep mentioning a PRV ? I thought you had an F&E tank i.e open vented system , is it a sealed system ?

 

[Patrick Hutchinson]

No it is open vented but after the pump is 2 valves and a prv. So should the valve be shut there is a run around to prevent cavitation, but my concern is that the prv is lift too soon so is letting the feed run direct back to the boiler as he pressure is too high, thus putting the boiler into fault as the temperature is rising too fast.
Theoretically this would only happen when the entire system is hot and the TRVs have closed leaving only the hall rad to absorb the pressure and flow so the prv could be lifting faulting out the boiler?

 

[ianmcd]

OK got it seen the pic in full now on my Ipad, that isnt a PRV (pressure releif valve) a prv dumps excess pressure to outside to protect a sealed system boiler, what you have is an ABV (automatic by-pass valve) which adjusts to allow the flow to keep the boiler from over heating depending on how many of your thermostatic radiator valves have closed, I think as you said that the pump you removed was sludged up that your problem may be a blocked cold feed, easy to test go to the highest radiator and open the bleed valve on the radiator and hold a bowl at the bleed point and see if you get a steady flow if you do it isnt that if you dont then it is that, if you dont get a steady flow then get a magnet and see if it sticks to the copper pipe where the cold feed is connected , if it does that is where your blockage is

 

[Patrick Hutchinson]

Should I check this with he pump on or off?, and is there a standard setting for the abv?
I bled all the rads after I fitted the pump and with the pump on, I get flow from every one but I did it with the pump on and system at full temperature.

 

[ianmcd]

try it with the pump and boiler off, but as you have managed to bleed the highest radiators it is unlikely that you have a blocked cold feed but only takes a few mins to test so give it a try anyway

 

[Patrick Hutchinson]

Nope every bleed is free flowing, any other ideas, also as I keep asking any idea of abv pressure setting?

 

[MrTherm]

@ Patrick Hutchinson,

For your system to function correctly the following conditions must be met...

1. Ensure the pump overrun is enabled and wired correctly at the boiler.

2. Ensure that when both zone valves are closed the pump continues to run for a short time ('pump overrun') - this will compare against the f25 code and when correctly set (as below) will not show.

3. Ensure that the AB valve allows water flow (when in No.2 condition) only.

4. Ensure burner is always off when in overrun condition.

To check No.2 condition, put a long screwdriver against the AB valve with the handle to your ear and listen for water (swish sound) - there must be no water flow through the ABP valve other than in the No.2 condition.

Generally, when set up and running as explained, pumps can be set to auto and checked as working ok.

good luck and regards.

 

[Patrick Hutchinson]

Ok the ABP valve is constantly passing It is a myson abv22, I can't find the setting chart for the valve, I believe that my boiler which is an glow worm hx24 minimum flow is 17l/s which is 1020lt per hr which I believe is 1m3/hr, my Grundfos pump is set at fixed speed 2 which looking at the pump chart is 1.8m head, but I can't find a setting chart for the valve to translate this into a setting,


Any advice?

 

[MrTherm]

As the two zone valves close, with the pump still running the increased pressure will open the AB valve but then it will close after the overrun period, so an AB valve constantly allowing flow is highly likely to be stuck or non responsive, check it out, a new valve might be the answer unless you can free or reset it.

You are right to keep the pump at manual setting for now as AB valves are normally adjusted to the relevent pump speed.

Using the 'ear test' is sufficient to set the bypass rate, if the swish is too loud (ie: fast) the rate should be reduced to a quieter flow.

Out of interest, how long is the pipe run from the AB valve back to where it joins the main return pipe?