I was recently explaining how the separate condenser on a single acting cornish cycle pumping engine worked. It was only when I had launched into my dissertation that I discovered that I did not know as much as I thought I did (there's a suprise).

As I understand it the condensate is exhausted from the condenser by the air pump which in turn discharges into the hot well and thence the water is cycled back to the boiler.

What I want to know is:
(1) Is the hot well part of the air pump or is it a separate item?
(2) Is the hot well merely a cistern for water discharged from the air pump or does it perform some other function.

Number two is the answer

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Years ago I spent time crawling about in the hot well beneath the floor at Dalton Pumping Station near Seaham Harbour in County Durham. The two Cornish engines there date from 1879 and supplied water for domestic use.
The hot well of each engine comprised a large square tank in which was placed the condenser and the air-pump, and normally the tank was almost full of water. A valve on the side of the condenser was activated by a rod from the engine and allowed a certain amount of water to enter so causing the vacuum within. The air pump was also activated by a rod from the engine and delivered into the hot well. I think there was a circulating pump to shift the water to a cooling pond outside and to re-circulate it back to the hot well tank so that it never got too hot. There was also a very rotten piece of wood on the end of a chain which seemed to be there to maintain a certain water level in the tank.
The retired engine driver who was caretaker at the time (1979) said the engines stopped working before the war but one was restarted in 1944 during a major power cut. Apparently the pump 400 feet below in the well was rusted solid and the only result was to tear apart the wooden spear rod - about 16 inches square - fortunately without damaging the engine!

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Years ago I spent time crawling about in the hot well beneath the floor at Dalton Pumping Station near Seaham Harbour in County Durham. The two Cornish engines there date from 1879 and supplied water for domestic use.
The hot well of each engine comprised a large square tank in which was placed the condenser and the air-pump, and normally the tank was almost full of water. A valve on the side of the condenser was activated by a rod from the engine and allowed a certain amount of water to enter so causing the vacuum within. The air pump was also activated by a rod from the engine and delivered into the hot well. I think there was a circulating pump to shift the water to a cooling pond outside and to re-circulate it back to the hot well tank so that it never got too hot. There was also a very rotten piece of wood on the end of a chain which seemed to be there to maintain a certain water level in the tank.
The retired engine driver who was caretaker at the time (1979) said the engines stopped working before the war but one was restarted in 1944 during a major power cut. Apparently the pump 400 feet below in the well was rusted solid and the only result was to tear apart the wooden spear rod - about 16 inches square - fortunately without damaging the engine!

What you're describing is the condenser cistern. The hot well sits in the condenser cistern. The air pump discharges condensate into the hot well.

I think we have a difference in terminology. I have always known of the condenser cistern as the hot well e.g. 'The Cornish Beam Engine' by D. B. Barton, 1969, p.24. "Note the separate condenser (and beside it the air pump) in the hot-well beneath the engine-house floor."
At Dalton the air-pump is a big circular vessel on top of which is a deep flanged part with an outlet at one side so that as the condensate was lifted up by the piston it could flow out into the surrounding cistern. That is the hot-well you describe.

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I think we have a difference in terminology. I have always known of the condenser cistern as the hot well e.g. 'The Cornish Beam Engine' by D. B. Barton, 1969, p.24. "Note the separate condenser (and beside it the air pump) in the hot-well beneath the engine-house floor."
At Dalton the air-pump is a big circular vessel on top of which is a deep flanged part with an outlet at one side so that as the condensate was lifted up by the piston it could flow out into the surrounding cistern. That is the hot-well you describe.

You are right in what you say but it was not beneath the floor it was situated outside at the collar of the shaft. The hot water was then returned to the cooling pond.

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Thanks to everyone who posted - I am more confused now than when I started this thread - further research is required - watch this space

Thanks to everyone who posted - I am more confused now than when I started this thread - further research is required - watch this space

Go here for a pumping station flow diagram, mine pumps may have differing detail.

http://www.croftonbeamengines.org/about.html 

Select 'How it works'.

Select 'Cornish Cycle' and scroll down to 'click here for diagram'

I believe the valve to the header pond is normally shut with all condensate being pumped back to the boiler.

Now that confusion reigns let us get even more so! :confused:

The hot well/condenser cistern is below floor level i.e. the base of the vertical cylinder usually sits at floor level, therefore the eduction pipe is below that and leads into it even though it is mounted on the opposite side of the bob-wall and accounts for the characteristic lower, narrow arch creating a path through the bob-wall. The hot well/condenser cistern sits at the top of the shaft as may be seen at the 90 inch engine, Taylor's shaft, E.P.A.L., near Camborne, for example, and traces of it may be seen at Frongoch and other former sites. In places like Kew Bridge P.S. the hot well/condenser cistern is tucked away below floor level out of site.

Now we come to the difficult bit - the two engines at Dalton P.S. have the hot well/condenser cistern below the floor and cylinder BUT on the same side of the 'bob-wall' or beam pivot. The other side of the engine over the top of the well is surprisingly open and uncluttered.

My query is why? All the diagrams, Crofton included, show the usual arrangement so why is Dalton different? Is it to do with this plant being the (alleged) only Cornish one to run on superheated steam at 40 p.s.i. or because of a later date, 1879?

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This is getting over complicated.
Most, in fact I would say all, steam engines that discharge to a condenser of some sort have a hotwell, this includes steam turbines.
Put simply the hot well is where the water from the condenser goes once its been extracted by the air pump.
From the hot well the water either goes back to the boiler as feed, a good idea as its hot and been boiled and is better for the boiler than raw water, or is dumped, not a good idea as you are wasting good water and heat.

This, the condenser is surrounded by a wooden cistern which is the hotwell
🔗Personal-Album-1228-Image-50843[linkphoto]Personal-Album-1228-Image-50843[/linkphoto][/link]

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Thanks to everyone who posted - I am more confused now than when I started this thread - further research is required - watch this space

Go here for a pumping station flow diagram, mine pumps may have differing detail.

http://www.croftonbeamengines.org/about.html 

Select 'How it works'.

Select 'Cornish Cycle' and scroll down to 'click here for diagram'

I believe the valve to the header pond is normally shut with all condensate being pumped back to the boiler.

My reading of The Crofton Website seems to confirm my original view that the hotwell sits in the condenser tank:

"The condensed water in the condenser chamber is extracted by means of the Air Pump(so called because there is also air in the condenser, and the pump extracts this as well). The Air Pump discharges the condensed water into the Hot Well which is the boiler feed reservoir.

The condenser chamber and associated pumps are contained in a tank of water to keep them cool. The water in this tank is continuously pumped out to the canal feeder by the Circulating Pump and replenished by fresh water tapped off of the rising main thus keeping the tank contents cool and maximising condenser efficiency. Here is a picture looking down into Crofton's No.1 Condenser tank with the components identified. "