Myson Velaire Oil Boiler Lock Out

Joined
13 Mar 2013
Messages
4
Reaction score
1
Location
Yorkshire
Country
United Kingdom
I have a 30ish year old Myson Velaire Oil fired boiler locking out. It runs for 5-30 minutes - sometimes even less if I reset it shortly after it locks out, runs for longer end of the scale if I leave it for 30+ minutes. I can hear the fan running for 10-20 second after I hear it stop burning, but before the lockout light comes on. It locks out if I have it set for hot water only or for heating + hot water. Except if the hot water is already hot it does run for 5-10 minutes then switches itself off before it locks out.

It has an Interoil 10 (I think) burner with a Satronic TF701B control box and a Satronic FZ711 photocell.

I've done some investigation and my current suspicion is the photocell, but direct replacements are no longer available. I've cleaned the windows on the photocell, but they weren't particularly dirty.

I've read that the MZ photocell might be OK, and I've also read that if I were to use a MZ then I should use a new control box. Would a new control box simply slot into place where the existing control box is?

I tried changing the jet nozzle yesterday to the 80S one recommended in the manual, but this didn't work as well as the 80EH jet in there already, so I swapped it back and have ordered a new 80EH jet - although I don't believe this to be the problem.

Any thoughts what my best plan of action is?

Thanks :)
 
Sponsored Links
Joined
13 Mar 2013
Messages
4
Reaction score
1
Location
Yorkshire
Country
United Kingdom
Is there any way to test the solenoid or pump or motor or photocell rather than just changing parts? I have a fuel pressure gauge, but will need a suitable fitting to enable it to go between the pump and the burner.
 
Joined
7 Feb 2008
Messages
23,730
Reaction score
4,738
Location
Northumberland
Country
United Kingdom
Is your pump a BFP21L3? If it is, you can fit the pressure gauge to the bleed nipple on the top.
I'd go for a new solenoid coil too. Often they are good when cold but fail when hot.....a resistance check could confirm but it's not a bad idea to have one in stock anyway.
The nozzle you used had a solid spray pattern (S) whereas the original one was extra hollow spray pattern (EH).
With this burner I find it sometimes impossible to adjust the pump pressure on situ due to the adjustment being on the side, so I run it up on the bench if access is tight.
John :)
 
Joined
24 Sep 2012
Messages
103
Reaction score
34
Location
Lincolnshire
Country
United Kingdom
Sounds like Classic Danfoss solenoid coil fault. Oh, and your pressure gauge doesn't fit between the pump and the burner so don't worry about getting any fittings for it.
 
Sponsored Links
Joined
10 Jun 2009
Messages
5,225
Reaction score
1,015
Location
Suffolk
Country
United Kingdom
:rolleyes: Some will do anything to avoid having one of us in to fix it (how dare we try to earn a living!) :rolleyes:
 
Joined
19 Aug 2008
Messages
1,640
Reaction score
536
Location
Essex
Country
United Kingdom
:rolleyes: Some will do anything to avoid having one of us in to fix it (how dare we try to earn a living!) :rolleyes:

I've got a spare FZ cell in the shed. Given prevailing supply and demand economics its available for £150 ;)
 
Joined
10 Jun 2009
Messages
5,225
Reaction score
1,015
Location
Suffolk
Country
United Kingdom
I also have 1 last FZ cell - but it won't put that boiler right I'll bet he needs an MSLA pump coil (I have 4 of those!!) ;)

I'd have that boiler running again in less than 1 hour but I'm probably too dear! :LOL:
 
Joined
13 Mar 2013
Messages
4
Reaction score
1
Location
Yorkshire
Country
United Kingdom
It is indeed a BFP21L3 pump. I have ordered a new pump coil and that should hopefully do the trick. I have learnt a bit more about the workings my boiler and hopefully saved a few quid in the process ;)

Thanks for your help and advice.
 
Joined
13 Mar 2013
Messages
4
Reaction score
1
Location
Yorkshire
Country
United Kingdom
The replacement coil did the trick. 5 minutes to change over and the boiler has been running all evening. Thanks for the advice.
 

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.


Are you a trade or supplier? You can create your listing free at DIYnot Local

 
Sponsored Links
Top