HRM Wallstar Lockout.

[Birmingham_Spanner]

I service a number HRM Wallstar boilers and live on a small estate built some 6 years ago where all of the properties had HRM 12/14's installed. I moved in about a year ago and have had no problem with mine but know of at least 4 others that suffer from regular burner lockouts that don't seem to be attributable to any single factor other than a build up of air in the supply line which can be seen in the flexi oil hose between non-return valve and pump.

My own also shows a large slug of air but has never causes the burner to go to lockout. All the other problem burners will fire as soon as reset and continue for weeks before gong to L/O again. If I vent the supply line at the pump and remove all air this does seem to increase the length of time before a repeat L/O occurs.

In one I have replaced the non-return valve with a new HRM supplied product which now incorperates the solder wheel fire valve in the same component as the N/R valve but this has not resolved the problem.

My question to all those oil experts out there is have you experienced a similar phenomenon? And of course if so, and you cured it, what did you find was the cause?

I am leaning toward a problem with the Danfoss pump but these are generally very reliable. Maybe it's just because the oil needs lifting a bit. In all cases the tank outlet is no more than 1.75 meters to the pump though and HRM assure this is fine.

I have contacted HRM who seem oblivious to any issues, though the redesign of the non-return valve did make me wonder.

A great design with a great burner and very good technical support (present issue accepted) makes me think this is just me. If someone else has experienced this I would love to hear from you cause i'm losing my marbles.

A tigerloop sounds like it may cure the symptoms and I often see these fitted to wall mounted boilers but never an HRM. Camrays and Worcesters maybe but not the otherwise flawless HRM.

Heres hoping.

 

[Softus]

My own also shows a large slug of air but has never causes the burner to go to lockout.

So did the Wallstar that I fixed last winter, and the slug of air didn't cause any problem.

...have you experienced a similar phenomenon?

Yes.

And of course if so, and you cured it, what did you find was the cause?

Dollops of sediment in the filter and supply line.

I am leaning toward a problem with the Danfoss pump but these are generally very reliable.

So too in my limited experience, but it's worth checking/setting the pressure.

Maybe it's just because the oil needs lifting a bit. In all cases the tank outlet is no more than 1.75 meters to the pump though and HRM assure this is fine.

I can't see what difference lifting the tank would make.

 

[wilhelm]

the slug of air is normal. an empty pipe is not, and could be leaking back past nrv.

make sure all joints are tight. flexi and nrv.


once youve eliminated an oil supply problem, ie oil falling back to tank overnight and or air. then carry out all the normal checks...ie start fitting loads of bits
most manufacturere fault finding guides are pretty good.

 

[simond]

Does sound like the NRV is letting by. Our Wallstars usually have two or three inches of air in the feed pipe, but there is oil on top of the NRV.

Assuming there is no oil above the NRV after a lockout (?) then it could be crap in the oil line causing the NRV to leak. Are the dodgy ones on metal tanks?

And good point, I wonder how the air gets into the transparent feed pipe if the NRV holds up? Never thought about it before.

Let us know what HRM say!

 

[Softus]

Assuming there is no oil above the NRV after a lockout (?) then it could be rubbish in the oil line causing the NRV to leak. Are the dodgy ones on metal tanks?

A fair question, bit I've had dollops of sediment out of a filter on the outlet from a plastic tank too.

I wonder how the air gets into the transparent feed pipe if the NRV holds up? Never thought about it before.

The tube starts off with air in it, and is never purged because the oil flow rate isn't fast enough.

 

[oilman]

...............
The tube starts off with air in it, and is never purged because the oil flow rate isn't fast enough.

But it IS possible to purge the line. Though it's not necessary as it's a pointless exercise.


Which burners are on the problem boilers?

It is not a general problem as the types of burners used on Wallstars are used on other boilers too. I do not have problems with more lockouts on Wallstars any more than other boilers.

Have had an occasional problem with lockouts which turned out to be the control box. This was not just change the box and it worked so that was the fix. It was see if it works, then fitting the old box to see if it comes back, then get rid of it again. This was over several weeks for each boiler.

 

[wilhelm]

the slug of air is always there cos its not under positive pressure . and its a one pipe system. the pump sucks enough oil to fire. it aint worried about sucking it so the whole pipe is full of oil .

anyway as i said. chuck loads of bits at it. bound to cure it.

 

[Softus]

But it IS possible to purge the line.

On the Wallstar?

Just out of interest, and I know that you said there's no point, but how would you go about doing it?

 

[wilhelm]

he means purge it to the point were you get oil.

on/off on /off

.............

 

[Softus]

he means purge it to the point were you get oil.

oilman said that there was no point in purging, so I don't see how he could have meant what you're suggesting.

 

[oilman]

But it IS possible to purge the line.

On the Wallstar?

Just out of interest, and I know that you said there's no point, but how would you go about doing it?

Suck oil up to the NRV (or the end of the flexi if it suits you), then use the burner pump and open the bleed. Even though you start off with no air in the pipe, it will collect after a while, so there wasn't any point in getting rid of it in the first place.

EVERY other flexi has the same air bubble if they are lifting oil, but they're opaque so you don't see it.

 

[Softus]

Suck oil up to the NRV (or the end of the flexi if it suits you), then use the burner pump and open the bleed. Even though you start off with no air in the pipe, it will collect after a while, so there wasn't any point in getting rid of it in the first place.

Oh. The bleed is mentioned in the MIs, so I thought you were going to come with something cunning.

I think we've had our wires crossed, 'cos my point was that the air bubble, that is contained in the tube at the time of priming, remains there forever and doesn't affect the operation of the burner, whereas you seem to have taken my statement to mean that I thought it was impossible to purge it.

 

[Birmingham_Spanner]

Thanks for all your replies. I must admit my own Wallstar has a considerable amount of air and seems to cause no problem at all. Very interesting to read the comments regarding it though.

The burners in all the boilers are Serling 40's. A great burner IMHO. The control box would of course be a very easy replacement and may well be very sound advice. As ever it is easy to start looking for difficult problems when the easiest solution may well be the cause.

I think I will swap out the box on one and monitor the situation. I will post back and confirm if this has solved the problem or not. After kicking myself several times of course.

Thanks again for all your help.

 

[Birmingham_Spanner]

Swapped control box (TF 830) last night. - Boiler was L/O this morning.

Have replaced Satronic 770s Photocell today. Looks like the pump tomorrow.

 

[wilhelm]

i would put a test gauge on pump.
i would also take a peak at ebi transformer..has it bulged?