water help no hot water

[jpbroad1970]

hi we have an issue with our heating and water system . new flow switch and new pump , system bled , all done by a professional but still no hot water or heating. when the plumber left yesterday we had boiling radiators and some hot water although the heating was switched off. my suspicion is diverter valve but unsure as to why nothing is working again now. boiler tries to kick in but says FD error (flow)

would be really happy for some advice as we have been 4 weeks without hot water no and the Mrs isn't happy.

thanks in advance
John

 

[John.g]

There is practically no flow at 11w on speed 2, which really just confirms more or less what you already know, 28W on speed 2 = 15 LPM but as its only on start up its hard to draw any conclusions from that.
From the above it would certainly appear that there is a very severe blockage(s) somewhere.

 

[jpbroad1970]

There is practically no flow at 11w on speed 2, which really just confirms more or less what you already know, 28W on speed 2 = 15 LPM but as its only on start up its hard to draw any conclusions from that.
From the above it would certainly appear that there is a very severe blockage(s) somewhere.

after start up it goes down to 27 until the boiler says no flow ( couple of minutes tops ) and shuts down. am reluctant now to try it any more in case we knacker the boiler up.

 

[John.g]

Probably misread your post #100, 27/28 W on speed 3 and 11W on speed 2 means no flow and would suggest something closed somewhere but you certainly can't keep firing the boiler up until you clear the obstruction or find what's closed which is why I suggested running the pump on a independent power supply with boiler off.

 

[jpbroad1970]

I'll try and find a wiring diagram for the pump and wire it to a plug to see what I can get on the pump to save my boiler

 

[jpbroad1970]

Was over thinking it , its only 3 wire connection isn't it was getting confused with 3 port valve

 

[John.g]

View attachment 39901


Was over thinking it , its only 3 wire connection isn't it was getting confused with 3 port valve

Yes, L-N-E, to your 3 pin plug.

 

[jpbroad1970]

beauty , that's my job tonight then.
correct me if im wrong
im going to plug the pump in so it is constant running open the 3 way valve to manual then go around bleeding the radiators checking the pump to see if the 27w rises , should I open one rad at a time or just go for it lol, I think @Brambles said start with all closed then open the nearest to the pump 1st then so on so on.

 

[John.g]

beauty , that's my job tonight then.
correct me if im wrong
im going to plug the pump in so it is constant running open the 3 way valve to manual then go around bleeding the radiators checking the pump to see if the 27w rises , should I open one rad at a time or just go for it lol, I think @Brambles said start with all closed then open the nearest to the pump 1st then so on so on.

If all the rads flow & return are open then, starting at the bottom, vent any air from each rad in turn. There is also a button to the left of the pump rotary selector knob, with the pump running if you press this once the pump is supposed to vent any air from itself (but not the system) I think it just modulates the pump speed up and down for 10 minutes and then returns to normal operation, don't know how effective this is but maybe do this before venting the rads, if you press this button twice, I think it does a different form of pump venting, again for 10 minutes before reverting to normal operation, I didn't utilise it when I changed out my pump but i suppose no harm in availing of it.
Also if you see any AAV (automatic air vent) anywhere, ensure the little sealing cap on its air vent nozzle is open and then re close it after venting any air.

 

[jpbroad1970]

thanks for that, I will have a look later , apparently the second press is for a manual start of the pump.
I couldn't find any auto vents anywhere ….is that usual?
should I let plenty of water out through the bleed screws?

apologies for so many questions

 

[John.g]

Once the air is gone...its gone, if you do get the pump power/flow up and are happy to run the boiler until the rads are hot, then I would suggest switching the boiler (& pump) off and then go round all the rads again and vent any air.
Re: AAV, I have seen them a few times on the top of oil fired boilers (don't know about gas) even with vented systems.

 

[Brambles]

JP

My understanding is that you cannot get hot water or central heating. At the moment , the boiler won’t fire and is showing a a defective flow error code.

If that is the case, your primary issue (and I think you have more than one) is between the heat exchanger and the bypass or three way valve. If that was not the case you would have either hot water or central heating. I am assuming that you service people have proved the three way valve, ensured that the by pass is operational. The latter should give you a simple (but too small a circuit for heat) to test the cold flow through the heat exchanger.

The object of this to get a hydraulic path established using one radiator to test out flow and return through one rad or indeed the HW cylinder ( if you prefer) to dissipate heat ( as and when you get it).

There is little (no) point in looking at the rest of the central heating system until you have the boiler on an established flow and then set the boiler to minimum gas rate for a hot flow test.

Any decent heating engineer would approach this in a similar fashion - start at the boiler, diagnose first, then implement the repair plan on a sequential basis. Once you have the boiler operating satisfactorily, then you can address the peripheral issues that either caused or contributed to the problem.

What I think you have experienced todate is people having a look, jumping to a conclusion, change a part, then wonder why when it does not work.

No or low flow ( if the boiler flow meter is reporting the situation correctly) is a serious issue. The protection on a boiler is to lock out the gas (or oil) supply when it (low flow) happens. The protection is not there to protect the heat exchanger against repeated firings whilst an engineer investigates the cause of the issue.

Once you loose the heat exchanger ( from blockage, distortion or leakage) - and that is not difficult to do - you will have a much bigger (more expensive) problem on your hands.

Your issue is not unusual, but you need someone who is familiar with fault finding and commissioning heating systems

 

[jpbroad1970]

all I can do is put in simple terms I understand lol

in brief the original pump packed up as did the diverter valve, I didn't realise the latter at the time. I fitted a new pump the same as the old one I took off which cured the problem other than the upstairs radiators coming on. it was a danfos and worked on speed 2 perfectly. I then turned all the radiators off to stop the heat. in the mean time we called the plumber to solve the issue, he tried then it all stopped working and said the replacement pump was old fashioned and fitted a new one. this again worked for a short period of time before I had to turn the new pump to number 3. I noticed he had left diverter on manual so I put it to auto and it felt all sloppy so I took the head off and it pretty much fell to bits in my hand. the first plumber then fitted a new 3 way then left it was all ok. when the boiler was idle over night it didn't want to go again in the morning. so while it was running its running ok but now we have nothing and that's where it sits,
I may have missed some steps but its about right.

all I know is we are now £480 lighter and still nothing resolved

 

[John.g]

So if you do decide to give the "cold hydraulic route" a go I presume you will put the 3 way valve actuator to manual open which allows water flow to both CH&HW.

 

[jpbroad1970]

So if you do decide to give the "cold hydraulic route" a go I presume you will put the 3 way valve actuator to manual open which allows water flow to both CH&HW.

I did try it but won't go above 27w.

Tried with all rads shut bar 1 and that did do anything either.

 

[Aire]

I did try it but won't go above 27w.

Tried with all rads shut bar 1 and that did do anything either.

Might be an obvious one and you might not know either but has any plumber actually checked the pump valves are fully open?

 

[jpbroad1970]

Might be an obvious one and you might not know either but has any plumber actually checked the pump valves are fully open?

Just checked, both fully open and dropped to 26w now

 

[John.g]

Might be an obvious one and you might not know either but has any plumber actually checked the pump valves are fully open?

That thought is in my mind as well, I would close each vale fully and then re open them, it should take ~ 4 full turns in either direction.

 

[John.g]

Just checked, both fully open and dropped to 26w now

Well, it would seem that you have a full fledged blockage somewhere, what purpose does the red (gate) valve adjacent to the pump serve.?

 

[jpbroad1970]

Well, it would seem that you have a full fledged blockage somewhere, what purpose does the red (gate) valve adjacent to the pump serve.?

Not a clue but it makes no difference if open or closed, there is little pressure in rads too

 

[John.g]

Last suggestion is to shut pump isolation valves, remove pump, crack open pump discharge valve for a few minutes and get a back flow and ditto with pump suction valve, also pour some water through pump ports to prove clear, don't throw away your other pump either just in case the new one has been affected by any magnetite in the dirty water.

 

[jpbroad1970]

Last suggestion is to shut pump isolation valves, remove pump, crack open pump discharge valve for a few minutes and get a back flow and ditto with pump suction valve, also pour some water through pump ports to prove clear, don't throw away your other pump either just in case the new one has been affected by any magnetite in the dirty water.

I've give up its getting too much for us. I know I keep saying it lol.

The 1st plumber took our new pump.

 

[jpbroad1970]

The plumbers that came yesterday, their boss is coming around Friday lunch, apparently he has more experience with blockages.

 

[John.g]

Very good. A bit academic now but I introduced some air into my own pump and then put in on speed 3, the power stayed at 27W (same as yours) and on speed 2, 11W, (again same as yours), I then put it back to speed 3 at 27W and couldn't get it above this despite venting the pump but when I returned to to speed 2 and again vented it (10 min vent) it settled at 24W on speed 2, so it would seem that these pumps are quite sensitive to any air ingress when running on full speed, I have now changed back to my normal setting of PP 4.0M running at its normal power of 17/18W.
I could hear some gushing sounds when the pump was on its 10 minute vent cycle.

 

[jpbroad1970]

I must admit I got some gushing noises too although I vented on 3 and it went straight back to 27

 

[John.g]

It would be nice to be be able to confirm to your plumber on Fri if you think the problem is air or blockage related so in view my own findings you might give it one more shot if pump is still on the plugtop. With 3 way valve open on manual start the pump and slowly turn the rotary knob anticlockwise until you get a flashing 4M , observe the power, if only - 8W carry out a pump purge and observe the power again, if 15/18w then the pump is circulating - 12/14 LPM, if still 8W unplug/plug in pump a few times at say 10 sec intervals....see what happens,.