I believe that there is a floating blockage in the hot water circuit f
my heating system. The system works for 5/10 mins then, when the
blockage hits a narrow spot, the boiler sounds like it bolis the water
and then turns itself off.

It has been there since we changed the three way valve last winter. I
have drained the system three times, via a radiator, but it does not
appear to find its way out.

Is there a drain point in the bolier?

Would a chemical additive remove it - I don't know what the blockage is
made up of?

What would a plumber charge for seeing to it?

garysz wrote:
I believe that there is a floating blockage in the hot water circuit f
my heating system. The system works for 5/10 mins then, when the
blockage hits a narrow spot, the boiler sounds like it bolis the water
and then turns itself off.
It has been there since we changed the three way valve last winter. I
have drained the system three times, via a radiator, but it does not
appear to find its way out.
Is there a drain point in the bolier?
Would a chemical additive remove it - I don't know what the blockage is
made up of?
What would a plumber charge for seeing to it?

My /guess/ is that it's a piece of grit fouling the pump impeller. Ergo,
when the pump stops, the grit is at the pump. Or some other intermittent
fault with the pump.

Owain

Owain wrote:
It has been there since we changed the three way valve last winter.

If it's broke after you've fixed it, you haven't fixed it.

I'd suggest that you check the wiring of the valve and ensure that it's
the right motorized valve head; there are 2 different Honeywell types,
at least. It may be that the 3-way valve is being closed by the
thermostat, but that the boiler isn't being turned off as it should be.
One of the 2 outlets of the valve should always be open, so this
doesn't quite explain the problem, unless you've got the heating valved
off.

The Honeywell wiring diagrams are available on their web-site.

garysz presented the following explanation :
It has been there since we changed the three way valve last winter. I
have drained the system three times, via a radiator, but it does not
appear to find its way out.

Which will probably be the actual cause of 'the blockage'.

If the valve is not wired and the actuator properly located on the
valve, then that might be 'the blockage'. Turn it on to provide hot
water, then lift the actuator off the valve spindle, then try turning
the valve by hand to the correct position. You should be able to hear
when the water is flowing through and determine which circuit is being
supplied with hot water by the pipes warming up.

--

Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.org

Aidan wrote:
Owain wrote:

I didn't :-)

It has been there since we changed the three way valve last winter.

Owain

The pump does not stop.

The 3 way valve was professional installed and works fine.

Interestingly the problem does not occur when both central heating and
hot water are on - presumably less pressure throught a large circuit.

garysz formulated the question :
The 3 way valve was professional installed and works fine.

Interestingly the problem does not occur when both central heating and
hot water are on - presumably less pressure throught a large circuit.

The problem IS the valve.

--

Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.org