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
they are in fact very efficient. But if run on leccy, not necessarily cheap.
Or are these hot water fan blown convectors?
I presume its a Johnson & Starley gas system
It'll be a complete rip it out and start from scratch job
In message , Endulini writes
'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
Cue resident loony extolliing their praises.
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..
My heavens, but you have the gift of prophecy!
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
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.
In message , Derek G. writes
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
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.
Sounds fairly typical of Scotlands approach to power.
To be perfectly honest that wasnt the character I anticipated.
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.
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
You didn't mention spiders. Or is that rumour not true?
Andy
I bought a new house in 1970 that had a warm air CH system, originally oil-fired, from a central distibution storage tank. There was no gas in the small town at the time. The downstairs ducts were all under the suspended floor. When town gas was supplied about 10 years later, most of my neighbours changed over to gas-fired boilers, and many also changed to radiators. I eventually bought a new gas-fired warm air boiler and retained the ducts. I found that they were perfectly effective - although I realised later that the original design was technically flawed.
If you study a/c systems in hotel rooms, you will see both inlet and outlet ducts for good circulation. Our builder had installed only inlet ducts - assuming that the return air would find a way back via gaps around the doors. Bad design that, just to keep the costs down.
David
Easily solvable though, with louvre style grills in doors
NT
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?
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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