Stanley Super Star 60 oil fired oven too hot

[spinynorman]

I have an oil fired 1989 Stanley Super Star 60 range which is used primarily for central heating.

With both thermostats set to 'idle' the burner runs for short periods before being shut off by the oven thermostat reaching maximum temperature even though the radiators are just about warm. At this point, turning the boiler stat down and then slowly back up produces a click at around 55c. The oven door thermometer would be about an inch past the 'very hot' section.

A couple of weeks ago I fitted a new oven thermostat which cuts out even sooner although the (original) thermometer needle is now right on the outer line of the 'very hot' section. It cuts back in a bit quicker too. At the same time I bought an 'oven protection plate' as it was on the available parts lists and sounded potentially useful. It's mounted by three bolts but I can't see these on my oven so maybe it's for a later model. I left this plate leaning against the oven side of the vertical oven baffle in the hope that it might help to block some more of the heat from the burner.

The boiler side baffle didn't look too bad but as that seemed like the only remaining thing to try I fitted a new one yesterday. It made a very slight difference but didn't really fix the problem. What did make a huge difference was leaving the over door slightly ajar just as a test. I'm reluctant to use that as a permanent remedy in case it causes damage.

Isn't there a better way of running the boiler at a higher temperature without wasting energy making the oven or kitchen unnecessarily hot?

 

[PullerGas]

I've fitted a few in the past but I can't remember how they're controlled, it's the single burner right?
Why not post up a copy of the wiring/controls for the appliance & we'll have a Butchers?

 

[Mike2007]

You might try fitting a control stat off a Rayburn if that Stanley stat seems dodgy? The oven operationl temperatures are exactly the same. Get one off a 480k.

 

[oilhead]

The oven protection plate bolts onto the side of the oven/combustion chamber.
When selecting the baffle position for boiler, does the boiler baffle swing right over to the cooker baffle?
Is the flow pipe from the boiler very hot?
Could your problem be with the flow thermostat that is switching off the boiler because you are not moving the heat from the boiler?
I would be inclined to look a little deeper into the efficiency of the pump and the general circulation of the heating system. Single burner ranges are lacking in most areas, but usually that the heating side impairs the oven operation by operating the pump overrun and isolating the burner. At the same time, fit your new oven protection plate in addition to the one that is already there.

 

[spinynorman]

Thanks for the replies

It's a single burner and the thermostat determines whether two wires are in circuit or not. If I could be sure that it wouldn't cause internal damage by exceeding design temperature I could try a different spec thermostat or just join those two wires for an unconditional circuit. The thermostat I replaced was the original as I've owned the house since 1993 and in hindsight probably wasn't faulty but had a slightly higher cutoff point.

The problem seems to be with too much heat reaching the oven and it's a crude design with the single burner. The baffle I changed had a few small chunks missing out of it but its main problem was that parts of the steel mounting had melted. The new one looks a lot more impressive with cast iron mountings and a much more positive feel when it's set in the angled position. There was a small gap between the baffles, which I understand is normal, but I reduced that to almost nothing by putting a metal object underneath the triangular socket of the rod for the oven side so I could swing its baffle slightly more towards the boiler baffle and have it stay in position after the control lever tool was removed.

I'd experimented a lot with pump speed and I'm convinced that the problem isn't with water being taken away from the boiler too quickly. I didn't like leaving the oven door open but it served to prove a point that the burner would stay on longer and allow the boiler temperature to increase. Last night it was the boiler stat which maxed out first and it made a huge difference to radiator temperature. I found a more acceptable short term cludge solution by closing the oven door and leaving the right side hotplate damper in the up position.

I'll have another look in the morning at mounting that oven protection plate. There's a small cast iron plate at the rear of the combustion area on the oven side but I really couldn't see how the bigger plate would be able to use the same holes. Reducing heat to the oven seems to be the solution so even if the plate has to hang one by a corner it's worth a try.

 

[Mike2007]

What about fire bricks/ insulation, maybe they are worn out thus giving more heat to the oven? If you added insulation to reduce transfer of heat to the oven you would give rads/pump a chance. That would just mean there would be a bit of "lag" getting the oven to heat up for meals? I am not very familiar with Stanley, but that's my guess.

 

[oilhead]

Your comment about the melting metal on the baffle is a little worrying. Have you, or a technician, checked the firing rate? Has it been serviced recently and a combustion test done? has anyone checked the flue for obstruction?

 

[spinynorman]

The insulation at the front and rear of the combustion chamber appears to be in good physical condition.

There are three pre-drilled holes in the oven protection plate with no corresponding bolts visible. The existing cast iron plate is secured by a bolt at the bottom and the head would probably be accessible from the upper oven area if I could remove four countersunk screws which hold a side plate which also serves as a shelf support. The two I tried are pretty firmly stuck when tried with a T-handle screwdriver. I chose instead to drill the top of the cast iron plate in situ and mount the oven protection plate on that, with the upper rear corners aligned. That made no appreciable difference.

I used to have servicing done once a year but noticed when I looked more closely that this appeared to be limited to making sure the burner mounting bolts were tight and vacuuming soot, both of which are important but I can do myself. I can remember only one occasion when CO was checked with a meter. The last guy just wound the air flap wide open without checking the result beyond the flame colour. I've reached the end of my limited expertise so I'll have a trawl through the local papers and hope to find someone who can go through it thoroughly.

 

[oilhead]

If the burner is over-aired, then it will be overfiring. You need to get it checked and rectified before you damage more than the baffle shroud.