HRM Wallstar air problem

[Malc]

Not sure I follow. The boiler is on a 15min cycle with a min run time of 4min (CM67 thermostat).

The running sound is nice and steady. When I had a solenoid coil go intermittent you could hear the boiler burn sound vary. I don't hear that now.

I haven't got a pressure gauge but the oil comes out under pressure if I open the air bleed screw so it doesn't look like it is struggling to get the flow.

Today's job is change the nr valve and see what that does to the bubble over the next few days.

 

[Malc]

Update for those following this thread.

I replaced the NV valve. Still getting slow air leakage. I have some heldite on order and will try that as I'm not convinces the white stuff is working.

What I have tried is ignoring the air bubble. It grows until it reaches a maximum size it seems where a bit of extra air added mean a bit of air pushed out and drawn up with the oil. I've had a couple of lock outs since the air has reached maximum but it also runs for days without locking out. Air bubble is unchanged so it isn't a case of max air bubble = lock out. I didn't know this before as when it locked out I bled the air each time.

I'm leaning towards it being unrelated to the air. Maybe the HT transformer. First job, since I have the heldite on order is to try that to fix the air leak, just in case it is the air that increases the probability of lock-out with out being 100% lock out.

 

[oilhead]

Have you still got the non return valve fitted at the tank? Ifso, it may be worth removing it as the pump has enough to do lifting the oil through one item of resistance let alone two. The M.I.'s advise against fitting one at the tank.

 

[Malc]

M.I. = Manufacturer's instructions? I checked with HRM before fitting the nv at the tank and they didn't see a problem. I would agree it does give some extra load to the oil pump but shouldn't be a lot compared with the force needed to push the oil through the nozzle.

 

[tosborne]

Hello Malc,
Reading your posts with interest. I have an identical problem with my HRM wallstar boiler which I have been working on.

I spoke to HRM technical support last week and they recommended a pipe jointing compound called "Plumba" to me. It is a clear silicone sealant and they said that because the system is under negative pressure (i.e. the pipes "suck" rather than have have water "blown" through them), PTFE doesn't cut it.

I remade some joints over the weekend and used this stuff and it seems to have solved my air leak. I left it to set for 24 hours before using the system (unhappy wife!). I will report back in a few days. You can get the stuff from Amazon. I had used Heldtite but it didn't work well enough for me...

Good luck with your boiler! Please keep us posted!

 

[oilhead]

M.I. = Manufacturer's instructions? I checked with HRM before fitting the nv at the tank and they didn't see a problem. I would agree it does give some extra load to the oil pump but shouldn't be a lot compared with the force needed to push the oil through the nozzle.

I think that HRM need to read their own literature from 5-6 years ago. They certainly advises against a NRV at the tank.
The extra load on the pump is not for pressure, but on suction and lifting. As the pump gets older and worn, it can become the last straw.

 

[Malc]

Update:

I think I may have fixed it. It's hard to tell as it can go days without failing.

The NRV at the tank didn't work and didn't seem to stop the air leak so it wasn't the oil falling back overnight that was the issue. I've changed the oil seals in the boiler fire/nrv valve and fitted a new new valve and changed the seals in the new valve. Still leaks air. Heldtite didn't fix the air leak either. Haven't tried plumba yet. Did try a o ring on the pipe olive as that seemed a bit loose (the pipe that is in the valve fitting) so I thought something squeezed in might help. Again no effect. It's almost like the air is dissolved in the kerosene and just comes out under negative pressure.

But, what I did try is changing the coil. What I noticed when I then fired up the boiler was how I could hear the spark. I could hear the buzz of the arc when that started (when the purge starts). Then after the purge there is the click of the oil valve and then the roar of the flame. I don't remember if I could hear the arc buzz when the boiler was new but I can hear it now so this has be a lot fatter spark.

I think the air leakage might just be a red herring. It was never clear how a bit of air stopped the boiler running anyway. The oil still gets though and after the air bubble reaches maximum and new air just gets sucked through with the oil. As long as the air leak isn't too big it continue to run. And when I checked daily I found that the air bubble reached maximum but the boiler still continued to run for days until a failure which supports it either being not related to the failure or just a minor influence on the likelihood of failure.

 

[tosborne]

Malc,
Reading your post with interest. I was having exactly the same problem with the boiler "sucking in air". I remade every connection perfectly but still it looked the same. I have since found out that it is more complicated than that - if you exposure kerosene to vacuum, often dissolved gases in the oil escape, and those are the bubbles you are seeing. It's not a leak, it is just entrained gas escaping. Your plumbing is fine!

With my system, I also replaced the coil and HT leads and I could also hear the noise of the spark, which I couldn't with the old coil. It makes the spark sound for about 5 seconds, by which time any gases have already passed through the nozzle and we are into the oil.

My system reached equilibrium after about a week (12" air bubble, any longer and air goes into the boiler). It has now been running perfectly for over 3 months!

 

[davidwf]

I am again experiencing this mysterious air ingress on our now 26 year old HRM 15/19....it is definitely coming from the fire valve end and tapping the valve provokes the odd bubble or two.
It has always had a small (about 2") static air bubble "as they all do" which, apart from the irritation of knowing it shouldnt be there has not caused any problems
For un-related reasons I replaced the oil tank 18 months ago, using new plastic pipework end to end with no joins but the issue was present before doing that
The pump was replaced 5 years ago
I have now replaced the fire valve and clear tube and sealed everything with heldite
I then dismantled the new fire valve and re-sealed every join on that with heldite
I tried running it from a 10lt jerry can below the boiler with a new short piece of pipe and new olives etc
.....AND STILL THE BUBBLES COME
The bubble "grows" about an inch a day until it gets so big the pump sucks in air and locks out

 

[oilhead]

is there any evidence of leakage around the pump shaft seal? I've seen this cause the ever growing bubble.
HRM always discount a NRV at the tank. At one I used to service, I 'cured' this problem by replacing the factory NRV with a conventional NRV and thermostatic wheelhead isolation valve combination. This was on a Friday afternoon before Christmas when all the merchants shut down. This lasted for at least 5 years. Your aversion to ptfe is a little misguided. A combination of this with Heldite gives good security on oil joints.

 

[davidwf]

thanks....as far as I can tell the bubbles are coming from the tank end, not the pump end
I did have that exact problem with the pump about 5 years ago (when it was a mere 22 years old!) where air was indeed being drawn in but our excellent HRM engineer quickly diagnosed and replaced the pump which cured the problem
there is no evidence whatsoever of any dampness etc around the pump

 

[Johntheo5]

I am again experiencing this mysterious air ingress on our now 26 year old HRM 15/19....it is definitely coming from the fire valve end and tapping the valve provokes the odd bubble or two.
It has always had a small (about 2") static air bubble "as they all do" which, apart from the irritation of knowing it shouldnt be there has not caused any problems
For un-related reasons I replaced the oil tank 18 months ago, using new plastic pipework end to end with no joins but the issue was present before doing that
The pump was replaced 5 years ago
I have now replaced the fire valve and clear tube and sealed everything with heldite
I then dismantled the new fire valve and re-sealed every join on that with heldite
I tried running it from a 10lt jerry can below the boiler with a new short piece of pipe and new olives etc
.....AND STILL THE BUBBLES COME
The bubble "grows" about an inch a day until it gets so big the pump sucks in air and locks out

Is this really plastic pipework or plastic covered copper pipework?, if the former is there any chance that oxygen can be absorbed through it like non barrier central heating pipework? Do you see the air in the tiger loop and if installed is this mounted high up above the burner level, externally? What make is it? and is the bottom of the tank located below the burner.

 

[davidwf]

It is genuine plastic pipe specifically stated for heating oil https://www.bes.co.uk/qual-oil-underground-oil-pipe-10mm-x-50m-13105/
I previously had copper pipe and had the same problem
HRM do not need tiger loop and specifically state not to use them
bottom of tank is approx 1.5m below burner - well within the specifications for this boiler

 

[Johntheo5]

Where do you see the 2" static air bubble.
I have a 18 year old Firebird 90S boiler with a Riello G5X burner and these are Riello's recommendations, my tank bottom is just above the burner so one pipe system has never given any problems.

 

[davidwf]

thanks for the detailed reply....this is since bleeding it out yesterday morning !
HRM specs say boiler may be up to 2.5m above oil tank....my local engineer says he has seen them well over 3m without problems