HRM Wallstar air problem

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Hi,

I have a HRM wallstar 12/15 : 11 (Date 07/04 I reckon, installed late 2004). It has an intermittent fault where it sometimes fails to run requiring someone to go outside and push the red button (usually when it is raining!).

There is a lot of air in the plastic pipe. I get rid of the air by wiggling the pipe when the boiler is running but it comes back over time. The assumption is that this large air bubble is the cause of the bad running, the pump suck air and so the burner doesn't light. It certainly is a new behaviour that occurred the same time as the bad running started.

So HRM tell me this is likely to be the non-return fire valve leaking down the shaft. Get a new one and new clear oil pipe - still does it. HRM say the shaft needs oil on it so pull it back and forth. Try that still the same. Take valve apart and get kerosene on shaft, no change. Grease shaft with vaseline - no change.

I've added a non-return valve at the tank thinking that is the problem is the oil dropping back then that would stop it and a non-return valve full of oil is likely to work better than one trying to stop air. Still get the air bubble so the air must be sucked in when the boiler is running.

I've applied La-Co SlicTite Pipe Thread Compound (which is rated for oil) to olives and threads. The cone joints of the clear oil pipe have been dry and with a smear of vaseline (I didn't want PTFE compound to get into the oil line).

Paper oil filter at the tank has been changed (and the olives there giving a coat of compound.

HT leads and ceramic holder for electrodes have been inspected (cracking of the ceramic can cause ignition failure). Just in case the large air bubble is a red herring.

I'm at a loss as to what could be causing this. I don't think it can be the pump because then the air bubble would start at the pump and it is in the centre of the clear oil pipe. There is oil after the bubble going to the pump.

The air bubble is consistent with air being drawn in with the oil and then the air staying at the highest point.

I seem to be left with either the new clear pipe is duff or I have a crack in the (copper) oil feed line which is too small to let oil out, just air in, but not enough air to stop the boiler running instantly.

The oil has been in the tank since the last top up in June, in case that is relevant.

Any suggestions?

P.S. Pump coil has also been changed. No sign of bulging on HT transformer.
 
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The large air bubble should cause no problems, as all wallstars seem to be like this, its streams of bubbles you dont want.

If its got a DKO control box on it, replace with a TF, the DKO boxs can cause some very intermittent problems, also if it has the older type EBI spark generator, then this too can cause intermittent problems, as they are not that reliable.

Are all the burner combustion setting okay?
 
Control box is DKO 970 mod 21 and transformer is Bentone Danfoss Type EBI 052F0037 (as written on them)

It's had a new nozzle. Front of nozzle is now black but I assume that is normal or maybe due to the air (or me getting rid of the air) causing burps?

I assume combustion is ok. No sign of smoke and it sounds ok. It seems very tolerant of air setting. I don't think it was changed for years. Last service the air setting was set to 2 (11% CO2) which produced a drone noise. This was upped to 4 (10.5% CO2) to kill drone which the oilman said was what it was set to before. HRM manual says air set to 4 and 11% CO2 so this wallstar is pretty right on the normal line. HRM reckoned that the drone was due to the fibreboard needing replacing so that was done this summer. No drone now. Air is at 3 AFAIR.

I don't see a steady stream of bubble but clearly there is some air getting in, just slowly over a day or so. I'm tempted to reverse the clear pipe so that it mostly below the oil pump level so air doesn't collect and see what that does. And I've read a suggestion that changing the o rings on the non return valve is an idea, so they are more springy. The NRV is new but then how long has it been on the shelf?

BTW according to this

//www.diynot.com/forums/viewtopic.php?p=877654#877654

DKO are better than TF as TF's fry the HT transformers.

Also, FYI, oil tank is not top exit but bottom exit.
 
Dynaflame has told you right regards the air bubble as long as it's static it will not cause any problems, this appears when boiler is above oil level and is being drawn up. There will be a sticker on the inside left of the casing explaining this. The EBI spark gens sometimes fail on these intermittently I've always put this down to the damp as they don't tend to be a problem on anything else they get fitted to.
 
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Could well be due to a weak Capacitor on the burner motor especially on cold 1st starts as well as other random times - been cuaght out on this one myself!! :oops:
 
Intermittent starts I would go for the solenoid coil first especially if it is a hot restart where it fails, then solenoid valve
as these can stick.

Next motor (caused by bearings becoming stiff) or start capacitor.

Easy enough to remove the possibility of oil by using a small tank above the boiler as a test.
 
Thanks for the suggestions. The fault is very intermittent. It can go days. So running with a small bottle of oil would show anything. I'd have to run for a couple of weeks like that.

Solenoid coil has been changed.

The air bubble isn't static but grows over days of running.

The motor seems to run ok. Same motor runs the fan and the oil pump. That starts 10s (purge time) before the oil is turned on by the solenoid so the oil is up to pressure (I'm sure of this as you can bleed with the screw during that time).

The times when I've caught it failing the motor runs as I can hear the purge so I don't think it is that. But there is a little dent on the capacitor so maybe I should rule it out altogether.

Transformer is a possibility and if it wasn't for the air bubble increasing I'd be more inclined to that. Of course maybe the air bubble is a red herring and the transformer is the problem. It is the usually on the first start that it stops working. Once it has run it seems to go one running but maybe that is because I get rid of the air.

I guess a plan would be not to get rid of the air and see if it fails more regularly. And if failure rate is the same then try a new transformer. I think I might also try replacing the seals in the old nr fire valve and then refitting that and the old pipe, just to exclude the new parts.
 
Solenoid valve stem as well?

Use the small tank of oil above the burner and keep it topped up.
If it works ok with that it is an oil problem or related to oil getting
to burner.
If the pump is having to work hard to lift the oil it can induce air into the link. But test with the small oil tank first.
Although HRM say a tiger loop isn't necessary it might be a good idea
or switch to a two pipe system.


Thanks for the suggestions. The fault is very intermittent. It can go days. So running with a small bottle of oil would show anything. I'd have to run for a couple of weeks like that.

Solenoid coil has been changed.

The air bubble isn't static but grows over days of running.

The motor seems to run ok. Same motor runs the fan and the oil pump. That starts 10s (purge time) before the oil is turned on by the solenoid so the oil is up to pressure (I'm sure of this as you can bleed with the screw during that time).

The times when I've caught it failing the motor runs as I can hear the purge so I don't think it is that. But there is a little dent on the capacitor so maybe I should rule it out altogether.

Transformer is a possibility and if it wasn't for the air bubble increasing I'd be more inclined to that. Of course maybe the air bubble is a red herring and the transformer is the problem. It is the usually on the first start that it stops working. Once it has run it seems to go one running but maybe that is because I get rid of the air.

I guess a plan would be not to get rid of the air and see if it fails more regularly. And if failure rate is the same then try a new transformer. I think I might also try replacing the seals in the old nr fire valve and then refitting that and the old pipe, just to exclude the new parts.
 
No, between swindon and bristol.

But, the problem is the fact the fault is so intermittent. If an engineer comes out, HRM or not, the boiler is work fine.

I've talked to HRM technical, they think the air bubble growing is suspicious as they say it should not do that.
 
What fittings are on the oil line? Compression or flared? If the tank is not to far try running a temporary oil line right up to boiler using flared fittings. I've done this sometimes to prove that air ingress is somewhere in the oil supply.

If you "flick" the NRV are you seeing bubbles? If so And if all fittings are tight then I would strongly suspect the NRV. you have done the right thing in terms of wiggling the spindle to lubricate a dry seal. Are you doing this and purging/venting the oil pump at the same time?
 
Fittings are compression but system has been running fine for years. I've use a liquid ptfe (rated for oil) on the olives. It's a non set so perhaps I should get heldtight(?) or something instead?

I've replaced the o rings in the old valve so when it stops raining I'll give that a try. I can't suck air on the old valve with the new o rings.

I've tried wiggling when the pump is running. That provokes bubbles occasionally.
 
Solenoid valve stem hasn't been replaced.

I did wonder about air getting back in from the pump is the pump solenoid valve was leaky. I looked at undoing the valve steam but it did want to move and didn't want to use too much force and break the pump (especially over xmas!).

Is the valve stem a replaceable part? Or does it have an oil ring that can be changed?

And I forgot to add that the oil tank is about a 12m pipe run (10mm copper pipe).
 
Solenoid valve stem hasn't been replaced.

I did wonder about air getting back in from the pump is the pump solenoid valve was leaky. I looked at undoing the valve steam but it did want to move and didn't want to use too much force and break the pump (especially over xmas!).

Is the valve stem a replaceable part? Or does it have an oil ring that can be changed?

And I forgot to add that the oil tank is about a 12m pipe run (10mm copper pipe).

I would buy some temporary PVC oil line and run a two pipe system
to the boiler with a new non return valve in the flow.
That will prove it without a doubt and can be installed quickly.
The pumps needs to be adjusted to run the two pipe system but this is only a screw inside the pump.
 
The air bubble grows if there is constant re-ignition on the burner, as the pump continually spins the oil in the pump and aerates it. The blacking of the nozzle also suggests this is happening.
It is worth trying another nozzle, and also running the burner with a pressure gauge attached to check pump.
 

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