2 problems, heating on when hw only and banging pipes

[ltodd2]

Evening all

Im hoping you can help me with the 2 problems i've got.
1, We have noticed that when the hot water is on only the rads are getting hot. Room stat can be set to 0. ch off on timer. this does not happen every time. Been pointed in the direction of the 3way valve. How do I test this. Its a danfoss hsa3 and is about 3 years old.

2. This has only happened about 10 times so is very hard to try things. In a morning we get banging sound from the pipes in the cupboard. I have managed to test a few things and it seems that the boiler is coming on but the pump is not. If left it all shuts down and trys again later. If I switch the system off and then on this clears it and all works. As far as I understand the pump should start first to get the water moving them the boiler starts and at the end the boiler goes off and the pump runs on for a bit. What could cause this? What controls the pump? When the pump is running it sounds normal.

Thanks

Lee

 

[gas4you]

Assuming you have a standard Y plan system, the 3 port valve will control the boiler and the pump. If one comes on the other will also. The banging sounds like a lack of circulation when the water has been heated by the boiler, so would point to the pump failed. The rads getting hot when only hw selected will be the 3 port valve faulty. It could be just the actuator head, or, in more rare circumstances, the valve body paddle stuck.

It could be that your system is sludged up and caused both to fail, but I would try replacing the valve head first.

 

[yerino]

1. 3 Port Valve, the arm is stuck in the middle so the water is getting past both ways (CH and HW)

2. Sounds like the pump is on its way out, whats its age?

 

[namsag]

Which boiler do you have , pump not coming on staight away can be down to a faulty pump over run stat

 

[ltodd2]

Thanks all for your answers. The boiler is Ideal, not sure the model but will find it. Whole system is only 4 years old. I have just removed the 3way valve head from th valve. The valve moves freely with no problems. I can move the leaver on the head and it moves ok.
How do I know which way the valve is when running. What does the leaver do. Can i open the head or will it all spring apart? Its a Danfoss HSA3.

Thanks

Lee

 

[gas4you]

DON'T open the head. If the head is on the valve will rest at dhw position. When on just ch it will be fully across and loose. If stuck on both it will be about 3/4 the way across.

 

[ltodd2]

Dave,
Do you mean the leaver will move. If so it never moves. Just ran the system with the head of the valve to see what it does.
The socket looks like a half moon with the flat side in the middle when power is off. Switch power on still same. Switch hw on and the flat side moves half way from middle to ch side on unit. ( Just did the test again to make sure and got a clicking from the unit and then banging in pipes cos bioler was on but no pump)
Which switched off the flat site moves all the way to the ch side. put ch on and it stays where it is. Im guessing its knackered cos that clicking sounded like a relay to me. Does this unit control the pump or is that the boiler or control units job?

Thanks

Lee

 

[gas4you]

If its clicking then sounds knackered. Valve head controls pump and boiler via the orange wire. How can you see where the spindle is if the head is on and moving?

 

[MANDATE]

If the system has been drained and all power removed from programmer the valve will go to HW only positon, this is achieved by the return spring.
In this position the outlet to the CH side is blocked off so preventing water entering from the valve end.
The lever engages with the quadrant in the head and is used to pull the valve to mid point, where the lever can be locked while filling the system and allowing water along both sides of system.

 

[corgiman]

I have asked before mandate but I have to ask again why the " "

 

[ltodd2]

How can you see where the spindle is if the head is on and moving?

I had the head removed from the valve so I could see if it was moving

Lee

 

[gas4you]

You are confusing me, which I know is very easy, but if the head is off then the spindle won't turn by the actuator, only manually.

 

[ChrisR]

Itodd, the heads sounds knackd but try this:
put the system on, thermostats turned up, HW only, boiler turned off so it doesn't get hot while you're playing.
Note the position of the D.
Then put the CH on at the programmer (CH + HW) and the D should turn 45 degrees.
Then turn the hw OFF and the D should turn another 45 in the same direction.
Then turn the HW back on and it should turn back 45, then turn the CH OFF and it should go back 45 more to the start.

You should hear odd clicks as the D approaches or leaves a position, as switches are being actuated.
If any of the above fails to happen, sling it.

 

[MANDATE]

If you have the head off, it should be easy to check if its functioning ok.
First you need to understand that with HW off and CH off there is still a wire from programmer to valve ( HW OFF) that is live and could be holding the valve in the CH only position,so the valve is not always where you think it should be.
The best approach is have someone turn off HW, then turn off CH ( even though CH is now off valve is held in that position ) Now observe bottom of acutator head and remove power going to programmer. This makes wire from HW OFF dead and valve should now move due to return spring right back to the rest position ie HW only.
Now put power back to programmer to start your checks.

With the head off and spindle anywhere between HW and CH position

First stage is to put HW on, boiler will fire up but valve will not move.
Next stage is to put CH on and because the demand is for both HW and CH the valve will move to the mid position ( this assumes stats are set to call for heat)
The next stage is turn HW off, This turns off the power going to the cylinder stat and stops the boiler, but also makes the wire from HW OFF live and this live drives the motor/quadrant/valve from mid point to the CH positon. The pressure from the motor holds it there for as long as is needed.
So in all you should be able to verify each half is operational.
You can if you wish have HW off and just CH only and valve should move across both halves, with a slight delay at mid point.
Another point to remember is that in normal use with the head on even though you have selected both HW and CH the valve only remains at mid point until one side of the system is satisfied.
Also you can while testing change the stat settings to see if the valve moves accordingly.
The clicking sound you mention sounds it may be something to do with the gears and pinion.

 

[MANDATE]

Hi corgiman. Interesting you should ask about I didn't know you had asked before.
To me it represents someone thinking of a solution to a problem.
Now you're going to suggest something different Yes?