The original heating on RM471 has never worked. When I bought the bus it had heater blower units under a seat upstairs and downstairs with 15mm copper leading to them. I suspect these were fitted when the bus was operated in Glasgow.

The fan motors didn't work and the pipes leaked so I removed them and have managed without any heat up till now.

This afternoon we removed the heat exchanger from above the cab which is fairly easy to do and were amazed how much brown sludge came out of it. We had to flush it through with a hosepipe about sixty times, rocking the unit to encourage the horizontal tubes to drain, before we cleared all the silt & sediment.

On refitting the heat exchanger it warmed up rapidly and both saloons were as warm as toast within a few miles.

On RM471 the ranco unit has been by-passed.

I now have to work out a way to shut the coolant off to the heat exchanger in the summer!

My bus number (if any): RMs 238, 471 & 2213

Chris - Whilst the heating system on 1699 has not been modified, I did change the heater excahnger unit and found that it made a significant difference to the performance of the heating system. The thermostat (ranco unit) can be accessed via the canopy flap and I think that many of these units have been damaged. I do have a spare so if you have problems with trying to connect your existing ranco unit back into the system then do let me know. But at least for now you now have a warm bus!

PS - I wonder whether you had any plans for a late winter meet up similar to last February when there was a gathering of RM's at the Shuttleworth Museum at Old Warden?

My bus number (if any): RM1699 Eastbourne Regent V 69(KHC369)

The ram air heater was not such a good idea for a bus that was intended to do a stop start service and at predominately low speeds. With no electric fan to circulate the heat, the RM was none too popular with passengers who lost their nice warm RTs to them. They are good on a long run though.

I was at NB when RMs replaced RTs on the depots major 65 route. The level of complaints in late october went from a trickle to a deluge by late november, (1975 I think)
I was not just passengers but crews as well. LT sent some engineering bods down to inspect the problem. All in suits, they fannied about a bit and decided that the system was adequate. Needless to say they took a bus out on the route and all sat up top at the front. The ran the route....you've guessed it ....Non-stop.

However, several weeks later, half a dozen new heater matrix units arrived from CRS along with controls and hoses with instructions to replace the units on six selected RMs. The removed units were to be sent to Chiswick for inspection and overhaul.

About 6 months later they were returned and had been descaled and cleaned.
In the meantime, the buses with the new units were warm and much improved over the rest. The fleet at NB was a mixed bag of nearing overhaul ex BW buses. NBA and parts were a big headache. So, we removed the matrix units from a few out of service awaiting parts vehicles and flushed them out using kettle descaler and a product called Barrs. I think the engineering gaffer paid for the stuff out out of his own pocket.!

The amount of furr and sludge flushed out was most telling. I don't think the heater system was factored into overhauls and just repairs or mods were carried out without much else.

We managed to get good all round heater performance on most of the depots RMs and they were noticably warmer than the LCBS RMCs that we often went out to in Kingston and Ewell.

We had just about finished the lot when the RMs started to get swapped for overhauled examples and it was really back to square one again!

The heater system was checked on overhaul, radiators and pipes renewed and all cables and switches replaced. The RM heaters were its true OK when moving but relied on the top radiator getting warm, this was helped by the blind being pulled in the cab, for a short while on starting out, but like a lot of things drivers just could not bothered or forgot to do it and then if they did they failed to release it blocking the flow of air to the vents, garages also failed to replace broken blind cords.

The high pressure filling system spoken about in another thread at GM and M removed airlocks another source of cold air in both RT and RM heaters. Glad the RT heaters worked at NB Jack, we couldn't even get our staff bus heaters to work, the upper saloon ones often blew cold although a good both feet down and drop into 2nd often shifted any airlocks.

My bus number (if any): RTL 960 RMC 1458 RM 1585 and several RTs

Lack of heat in a stationary RM was indeed a design failing given that stop start slow speed working was always going to be more usual than high speed non stop running. If anything accentuated this it was December Sunday evenings in the West End when gridlocked traffic caused by Christmas light sightseers meant passengers froze in RM`s that could take well over an hour to cover the distance from Hyde Park Corner to Haymarket.

Remember RM 931? The one that was so heavily canabalised during and after the spares shortage in 1973 that it finished up as a derelict shell dumped at the back of BX garage. Quite a surprise when it was finally rebuilt in late 1980. Outshopped from Aldenham to Stamford Brook as RM 848 in late January 1981, it had the best heaters I`ve ever known in an RM. Presumably because of new units and pipe work.