Replacing Hot Air Heating

Hi All,
A flat that I've been looking at with a view to purchasing is heated by an old hot air blower system. I'm not familiar with these systems but they don't strike me as very efficient are they straight forward to replace or are there likely to be some lurking issues (I appreciate that it will obviously depend on the actual system but in principle might there be some problems)?
Cheers
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Endulini wrote:

they are in fact very efficient. But if run on leccy, not necessarily cheap.
Or are these hot water fan blown convectors?
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I presume its a Johnson & Starley gas system
It'll be a complete rip it out and start from scratch job
--
geoff

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Since it is struggling to reach even 40% efficient when it gets to you, that would be difficult. That's partly why it's more expensive than gas.

I rented a house with a J&S warm air system many years ago, and I quite liked it. Very quick warm up from a standing start. However, it would be a disaster if anyone smokes, and it caused dryness which one of the other occupiers claimed caused problems with contact lenses.
I believe they do drop-in modern replacements for older systems, if you do consider keeping the infrastructure.
--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
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Hint: Electric storage heaters & panel heaters work fine for flats - once you have 50mm Celotex on the walls.
I would fix the insulation first.
Oil really is likely to be 300$/barrel by 2020 which basically means the average heating bill will be £2800-3700.
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'60's build?
Off peak electric, *concrete block*, ducted air. My wife has inherited a flat which originally had such a system.
There were two main problems. The heater elements age and need replacement. The system is probably undersized for maintaining comfort levels by late evening which encourages occupants, particularly tenants, to minimise ventilation leading to condensation on cold outside walls.
Flat ownership is a bit of a minefield in that what you can do to the outside walls may depend on others. Cavity wall insulation operators would not look at ours, there was a great to do over fitting plastic double glazing, gas fired wet heating was initially resisted although most have now been converted.
The gas fitter who installed our system said he had found asbestos insulation but I did not see any evidence and there was no disposal charge.
You could look at other flats in the block and see what other owners have done. Gas flues, double glazing etc. There will be a *management organisation* who will have final say on such matters.
regards
--
Tim Lamb

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Cue resident loony extolliing their praises.
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cynic wrote:

Hot air systems are very very good at getting a space up to temperature quickly with very few hot spots.
They also are compact.
Their efficiency and cost depends on how they are driven..
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On Mon, 30 May 2011 10:20:59 +0100, The Natural Philosopher

We had a Johnson & Starley gas system. It did indeed heat the room air very quickly. Unfortunately all the furnishings and fittings etc stayed cold to the touch for just as long a time as a wet CH system.

Absolutely untrue of the "Electricaire" systems.

The joints in the ductwork in our system were sealed with ("Waddya Know!) duct tape which dried out, went crispy and dropped off, leading to loss of hot air.
It also blew dust about the house and the main circulating fan was unbalanced, hence noisy, from day one.
Derek G
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Ssh ...
resident loony's been quite for a while

Although modern J&S systems have an electrostatic dust collection system
As for the fan - you should have rejected it if it was new - the additional problem is resonance in all that metalwork
Not sure I'd want one
--
geoff

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Derek G. wrote:

well don't blame a class of heating for one badly implemented system
I was merely trying to make the pit that there is nothing wrong with hot air blowers per se. Its how they are installed and what they run off, that makes for a good or bad system.
I've got blown convectors plumbed into the hot water circuit. Neat and compact, just a bit noisy.
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On 30/05/2011 11:36, Derek G. wrote:

You didn't mention spiders. Or is that rumour not true?
Andy
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wrote:

The fan only runs in the heating season.
We did gcome across the occasional crispy specimen dessicated by the hot air at 75C.
Derek G
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On Mon, 30 May 2011 10:20:59 +0100, The Natural Philosopher

The one we had in Scotland certainly did that. When it came on the cat was flung across the room and left clinging to the curtains. Conversation became impossible and TV could only be understood by lip readers.

I'm not sure the 8ft x 4ft x 4ft container of bricks heated by electric elements which filled what would otherwise have been a useful storeroom by the front door could by any stretch of the imagination be called "compact".

The room the bricks were in was very warm, very useful for helping epoxy glue to harden. Unfortunately the heat loss during the day (when no one was in) was such that by the evening nothing much remained. Fortunately the design was so bad that the large contactor used to change from peak to off peak had fused shut into the off peak mode.
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Peter Parry wrote:

Sounds fairly typical of Scotlands approach to power.
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On Mon, 30 May 2011 10:20:59 +0100, The Natural Philosopher wrote:

But unless all the rooms are conveniently arranged directly around the WA unit there may be permanently cold spots. Some otherwise very nice 60s Modern flats round here have the unheated bathrooms because they don't adjoin the WA units!

Er, eh?! A full-size cupboard devoted to the WA unit and ducting compared to a suitcase-sized gas boiler? Plus a HW cylinder and storage tank because you don't get 'combi' WA units.

The gas-fired units I've seen have permanent pilot lights on both the main WA unit and the separate water heater part, hence dinosaur levels of efficiency. I'd guess newer models might get up to standard efficiency. Do they even make high-efficiency (condensing) models?
--
John Stumbles -- http://yaph.co.uk

It's bad luck to be superstitious.
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My heavens, but you have the gift of prophecy!
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On May 30, 11:26 am, % snipped-for-privacy@malloc.co.uk (Steve Firth) wrote:

To be perfectly honest that wasnt the character I anticipated.
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Yebbut, still a resident loony. No doubt the other loony will be along as soon as nursey releases the strait jacket and attaches his headstick.
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You havent told us what trype of system this is yet.
If its gas fired ducted hot air, theres no reason to replace, as long as you dont mind mild background noise when it runs. The boilers to use in such systems are still being sold new, albeit by only one company.
If its blower radiators on a water based system, these perform much the same as ordinary CH, but the rads are much smaller and make a little noise.
If its fanned storage heating, they're bulky and csot more to run than gas or oil, and old units may not store enough heat to keep a place warm all evening. Insulation can solve this, or replacement new heaters are better at predicting heat needs and storing enough.
NT
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