Ideal classic nf 40 sealed system boiler with megaflow tank

[twgas]

I dont think the classic has a pump over-run.
You ought to leave the boiler alone and get a RGI to check that you have not left it in a dangerous condition, after playing about inside it.
As for the pump running, it's probably a stuck mv.

 

[southseapirate1]

Hi Spraggo,

Just been going through it again and there only seems to be two sensors one is def a overheat switch(for sealed systems, mine) and there is also a temp stat sensor.

The link attached shows ideal models NF series 50 upwards but it's exactly the same as the one ive been following. On frame 36 under the title instillation it shows the switch and the sensor. Can confirm that there is nothing else that enters the heat exchanger. So i'm a little stuck now.

The link is http://www.idealheating.com/downloads/manuals/111752-2.pdf

kind Regards
Dave

 

[southseapirate1]

Mick,

Think you are right so with the pump running constanly I've two MVs in the airing cupboard. Please can I ask what checks I need to do to confirm that they are in the right position as demand requries.

Kind regards
Dave

 

[Razor900]

I'd stop playing with the boiler and check the external controls

That's it you've hurt my feelings now

 

[twgas]

razor, I hope the thanks has cheered you up.
You need to check the end switches in the valves, with a multi-meter, if you have one. Power off, disconnect switches (make a note of where they are connected), test each one for continuity.

 

[spraggo]

Mick,

Think you are right so with the pump running constanly I've two MVs in the airing cupboard. Please can I ask what checks I need to do to confirm that they are in the right position as demand requries.

]

Now we are getting somewhere, as I mentioned earlier I did not have the manual for this boiler at hand. You now state that you have two MVs, so the first thing to do is look a for lever on these valves, which could be situated on the sides or the end of them. They will be sticking out from a slot, and at either end of this slot will be marked Auto and manual. Check to see if you can move these levers back and forward along this slot with no resistance, with hot water and central heating switched on, and again with the hot water and central heating off. usually with the hot water cold and the central heating cold the levers should be in the AUTO position. It would be a great help if you could identify the make and model of these valves complete with any numbers that they have on them ie, Honeywell 4073A etc. This would also help to trace the wiring.

 

[southseapirate1]

Spraggo,

Many thanks will check and let you know.

Regards

 

[southseapirate1]

the MVs make are sunvic they have been marked up by the installer as CH and HW which is handy. No mid position only normal use and Flushing use indications. Thye are in the normal position at present.The boiler is currently off with no demand from the timer but as before the pump is running constantly. Just to recap I have a mega flow sealed system. There is a balancing Vv too which connects the heating side with the hot water side. Presume this should be open about half way???

Thanks

 

[spraggo]

We can now narrow your problem down to the ch mv, This is driven by the room stat. So, with the central heating switched on, check if the pump starts or stops when you turn the rom stat up or down. If the CH MV does not operate when you do this then the problem is either the room stat or the CH MV.
If the system worked be fore, and you have not altered this balancing valve then leave it where it is.

 

[southseapirate1]

Hi Spraggo

Thank you for your further advice

Turned off the hot water demand and just left the heating demand to once. Turned the thermostat to it's lowest position left it for about 15 mins but the pump is still turning. I can confirm the hot water had been on and so had the heating before testing it this way as kindly advised. Balancing Vv left alone I remember only a few days back hearing the MVs when the heating or hot water goes of. You can hear the little motor doing its job. Is there a way of testing them by hand??

I did leave the system on whilst at work with the hot water and heating demand set in the off position hoping when arriving home the pump may have stopped but unfortunately it hadn't. I didn't note what the room thermostat at that particular point

Regards

 

[spraggo]

You don`t say that your hot water is to hot so therefore the HW MV seems to be working. Therefore I would suspect that the CH MV is faulty. you mentioned that the slot on the valves were marked, flush and user, flush = open and at this end of the slot you are able to lift this lever into a little recess in this slot to hold this spring return valve open. First make sure that some one has not accidently lifted the lever into that position. You did say that the valve lever was in the normal position, did you mean flush, or user position?. When there is a demand for heating the HC MV will open and send 240v, from a permanent live through the the orange and grey wires connected to the valve, to the boiler and pump. The HW MV will also do this when there is a demand for hot water.
It follows that if either of these valves does not shut when demand is satisfied then the boiler and pump will continue to run. To check this you will need to make sure that there is no continuity through the orange and grey wires to the valve when it is closed, If there is continuity then the valve is faulty.

 

[southseapirate1]

I can confirm that the MV for the heating is working correctly. The heating went off as instructed by the timer and the MV operated. I can say the hot water is a little hotter than normal even though the cylinder stat is set at 55 degrees. I deselected the hot water so instructing the hot water to go off but the MV did not operate. I will check tomorrow with a multi meter. I'm fairly sure the hot water MV is at fault.

 

[spraggo]

Hi Dave,

Well done, I think you may be able to get just the new head for these valves, its all according to the letters and numbers marked on the head.
But make sure that the spindle turns freely in the valve body, if it does not, then I would advise you to renew the whole thing. Any make 22mm two port spring return valve can usually replace it, it does not have to be a "Sunvic"

Regards

spraggo

 

[southseapirate1]

Afternoon Spraggo,

Here goes please bear with me. I isolated power at fuse spur at boiler marked CHMV and HWMV removed carefully and tested continuity after first testing the multi meter continuity. the CHMV was 0 and the HWMV was 1. Turned power back on and did another test with no demand set on the timer for either HW or CH plus thermostat was set to min. CHMV was 0 HWMV was well above 1. Demanded hot water and heating on timer and moved thermostat to 22 degrees and tested agin CHMV ( saw motor wheel move on this one) was 0, HWMV was 1.

I am I right in saying that the HWMV is US and needs changing??

Think i'm going to need an crimping set and a mini soldering iron as the grey and orange wires are soldered onto a tiny circuit board which slots into the side od the motor

 

[southseapirate1]

just to add from a question you asked previoulsy the lever position on both valves were set to "normal use only" the other set says flushing only. Hope this all helps!Hoping victory is near and I can wiz down to the plummbers merchant and get the part.

Kind regards

Dave