Dehumidifier information (Long)

Gentlemen,

I recently bought a dehumidifier to hopefully reduce the rusting problems in my "workshop". Hopefully the following may be of interest

The Dehumidifier purchased was a New Meaco DD122FW MK3. This is a dessicant type dehumidifier purchased particularly as it will run down to 1 deg C. Cost was £148.99 inc carriage The "Workshop" is a garage attached to the house.

5.7m Long x 3m Wide x 2.2m High Single brick construction on 3 sides double on the fourth. The "up and Over" door exists but has been clad on the inside with 70mm thick foam. The flat roof ceiling is plasterboard covered but with no insulation. An externally venting tumbledryer is used in the garage. I have a Lidl Temperature and Humidity sensor in my adjacent office with an additional remote sensor placed in the garage. When placed adjacent to each other they gave equal humidity readings (normally about 68% in the office) The Meaco unit was installed on the 3rd of February at 11.00 am and left to run in "Auto" continuously. (Auto should control to a humidity of 55-60% RH). At that time the Humidity reading in the garage was 87% and the temperature 7.8 deg C. The unit was connected via a power monitor. After 24 hours the Humidity was down to 69% at 9.6 deg C and 3.15L of water had been collected with a power usage of 8.4Kw hrs. The unit runs at about 27watts with the fan on (continuous) and about 400watts when the humidistat kicks in. On the 10th of February (1 week) at 11:00am the unit had pulled a total of 8.12L of water with a total usage of 24.64 KW hrs. The average humidity over the week was a pretty constant 68%. Lowest temperature (seen) was 5.2 deg C and highest 10.8 deg C. (No additional heating was used). Little work was done in the workshop (too cold) but the tumble drier was used a few times. If we consider that steady state conditions had been achieved after the first 24 hours then the future consumption is likely to be (24.64-8.4)/6 Kw hrs per day = 2.71 at my current electricity charge that is £0.30 per day.

The fact that the unit did not achieve the expected 55-60% humidty level was noted. The remote sensor was checked for calibration as per info seen on the web (salt test) and was found to read 82% when it should have read 75%. This infers that the current reading of 68% is actually 61% which indicates that the Meaco control is reasonably close. (All of the figures quoted above were actual not adjusted readings).

I will continue to monitor the unit at different settings and will report back if any changes result.

I hope that the above is of interest and would be VERY interested to hear of results from any Compressor type dehumidifier installations for comparison.

Richard

Reply to
Richard Edwards
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I've had an Ebac compressor type running automatically in the machine tool section on the back of my garage for about the last 16 years. Quite happy with it and has not given any problems so far other than some degradation of the chipboard base. It was selected as it was rated to run down to 2C. I haven't done any energy consumption checks. Water collection has been automatically drained into a nearby drain for maybe a decade, but before that I had to empty it. The tank is about 4 litres and at drier times of the year you might empty it once a week, at damper times daily as it could fill the tank in a day.

Reply to
David Billington

if it uses all that much electricity ..i dont understand the advantage over a compressor type one ..

best thing you can do is vent the tumble dryer to outside ..

its rapid heating that causes the condensation .

the big lumps of cast iron remain cold and don't warm up as quick as the rest of the room ..and then they get condensate on them .

keep the room at one temperature 24/7 ..and you want get condensate no matter if the humidity is 90 percent.

all the best.markj

Reply to
mark

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I have no knowledge of how much a compressor type would have used in the same circumstances!

The drier is vented outside see "Externally venting" above

Granted

What temperature would you suggest? With outside temperatures the way they have been recently I feel sure that the costs would be even higher.

Richard

Reply to
Richard Edwards

WELL its swings and roundabouts ..

i reckon the heat from the dehumidifier maybe fighting with the problem ....its raising the temp slightly periodically..as its dehumidifying.

i would plumb a radiator in there......and have it with a valve stat ..to keep it at say 12 degree c.

insulate the place well...........and you've then got a nice warm environment to work in ..and no condensate.

me ..im waiting for this whispergen thing to come out (available from E-ON soon)...then I'm going to pipe the central heating (hydronic radiator ) over to the workshop ....make 32 pence for every unit i sell back to the grid.

SO IT SEEMS ..put me right if I'm wrong

and hopefully it will work out cheap .....hopefully, 'cause i cant find any real figures from real people ..

they have them all over Germany ...NICK !

any comments advice about this whispergen and the new feed in tariff much appreciated .

as all i see it ..it looks like win win as long as i jump on it soon enough, before the gov changes its mind in a few years time.

BTW this whispergen .is the size of a washing machine ..having a boiler in the workshop ..instead in the house ..is another way to keep the place cosy...only works if you have a joined on garage and you never use it for cars though.

all the best.markj

Reply to
mark

The idea of running the central heating all night does not appeal!

No argument.

If going hydronic I suggest that you do not bolt your machines down

E-On's site says should be ready for 2009 Whispergens are NOT cheap to maintain. I have a little experience as I installed one in a boat a while back.

Richard

Reply to
Richard Edwards

keep the room at one temperature 24/7 ..and you want get condensate no matter if the humidity is 90 percent.

all the best.markj

--------------------------------------------- True, but you will still get rust.

Cliff Coggin.

Reply to
Cliff Coggin

:

HI Richard

i don't know anything about the maintenance issues ..please explain .. they guy from the UK whispergen headquarters told me the boilers had a

30,000 hour lifespan .. he said :- that is on-time 8 hours a day ..which equals 15 years ...or more.

and he also the latest ones are being built in a brand new factory in Spain ..and are a different design to past ones.

whats the situation to doing you're own maintenance ..with gas i don't know if aloud

but he said something about a maintenance contract.

i suppose ..i will have to add up all the pros and cons .. the price on the e-on site, he said was out of date ..and the price when released would probably be over =A34000

no subsidy's now that they have changed the subsidy to the tariff ..and not to the buying price .

all the best.,markj

Reply to
mark

It has been "soon" for about 5 years. There have been a number of trials but I believe all were stopped because of unreliability.

Unfortunately the idea, unless you have a small to medium hotel, simply doesn't make economic sense. It works off the waste heat from the boiler. If you have a modern boiler they are about 90% efficient so not much waste heat to begin with. The Whispergen captures about

25% of that. If you insulate your house well your heating bill goes down and the amount of electricity you generate goes down.

For something like a 100 bed nursing home with a high constant temperature they may make sense, for a normal house it is unlikely you will ever recoup the cost.

Cheap they are not.

With a modern boiler the case losses are about 100W which isn't going to keep any workshop warm!

Reply to
Peter Parry

They are complicated devices so few fitters understand them, those that do charge a premium. Up until now they have proven to be unreliable and very expensive to maintain. Spare parts can be hideously expensive - see

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for the diesel version spares to give you an idea. For example the electronics module is a snip at only £1,200 (ex VAT). The installation and purchase cost is being heavily subsidised by the power companies - the spares and running costs are not.

They don't guarantee them for 15 years do they?

They have many moving parts, rotating bits and electronic controls, it is unrealistic to expect them to last as long as a conventional boiler. 30,000 hours may be an optimistic design life - it certainly isn't going to be their service life unless you treat them like Trigger's broom.

So leave it a decade and see if the new ones are any better than the old.

They are too complicated for most fitters.

That would certainly extinguish any saving!

Reply to
Peter Parry

Strikes me that it would be more cost effective at the moment to use a CHP plant based on waste heat recovery from a NG fuelled spark-ignition engine powered alternator rather than a Stirling engine.

Mark Rand RTFM

Reply to
Mark Rand

There was just that sort of thing mentioned on the local news in the west country maybe 20 - 25 years ago. IIRC a Ford Pinto engine generating electricity and the waste heat used for building heat in a complex. They mentioned an upshot of the engine running at constant speed, well below peak, was that the engine life expectancy was much higher than in an automotive application.

Reply to
David Billington

Of course the best solution is to use a computer. Very few moving parts (if you don't count holes and electrons) and all (if you turn the monitor and speakers off) of the electrical energy comes out as heat.

That way whatever you do on the computer costs you nothing, though with the monitor and speakers off it might not be much use :)

Reply to
Cliff Ray

Thanks Peter ..that's a good insight....yes the spare prices in that list are horrendous ..stuff that...whispergen ..too good to be true by the looks of it.

PS.. I heard that the trials were a success ..not a failure with unreliabilty...there are various pdfs about on the net that say so.

It's the scare stories about gas and electricity prices going up by another 25 percent in the next two years that are worrying me ..

I had a waste oil system i designed on test that worked very well ...and cost me almost nothing .. it did all the heating ...and would let me use an open hose with hot water coming out of it all day without it cooling down. Sadly could not get away with such a system in the suburbs. if i lived out in the wilds..a secluded house ..i could do it ..

FORD PINTO ... surly a diesel engine would work better and be cheaper.

all the best.markj

Reply to
mark

I have built several workshops over the years and can not stress the advantages of insulation enough, sort out the roof by fixing a minimum of 3" of insulation on the inside by fixing wood beams and using 3/8 plasterboard to hold the fibereglas up. After that do the same on the walls using rigid glass bats and cover with 1/2" board. The result will be an even temp summer and winter, low heating cost and no rust. If you need more help, PM me Peter

Reply to
Drawfiler

I remember a feature on ''Tomorrow's World'' at about that time. They used a Fiat Diesel engine of around 50BHP. The electricity generated and the waste heat fed a small block of flats.

I think, as mentioned a while ago, the economics don't word for a small private dwelling - maybe there's scope for some sort of DIY option along the lines of the old Lister Start-O-Matic?

About 10-15 years ago I manages to have a look at Manchester Airport's CHP plant. Two V12 Mirlees Diesels (AKA ship engines) running on 95% natural gas and 5% Diesel (the Diesel acted as ''the spark'' so I was told) You could walk along the valleys between the banks!

Julian.

Reply to
Julian

It appears the Whispergen recovers about 5-10% of the heat energy in the boiler exhaust, not 25% as I mentioned. It is also worth pointing out a slight fallacy in the various "return on investment" figures being bandied about suggesting you can achieve the equivalent of 8% or more. You can't.

Even assuming all the optimistic figures are true what you are looking at is not an investment. If you invest money then at the end you get back your capital (the amount you invest) plus interest earned over the period. With this scheme your capital investment at the end is worthless. A 15 year old boiler (or windmill or solar panel) has little or no value so your investment is lost. All you are left with is the small annual return.

Spending you money on better insulation is a far better bet.

Reply to
Peter Parry

The insulation is done ..i cant do any more ..

OK you've put me off the thing mentioning the.possibility of loosing all savings in one repair bill .

but on paper, if it didn't bugger up, it still looks good ..

30 pence per unit back will pay for this boiler in half its life's span.

i don't have a boiler at the moment .

thats how i see it, looking through my rose tinted sunglasses.

A 5 year free parts and maintenance contract ..of =A375 per year would also sell the thing to me.

The thought of a warm workshop ..on the cheap is also a nice thought. (thats what gives me the extra capacity for it)

The thought of gathering and chopping wood, the alternative, is not a nice thought.

I will see what the contract is when it comes out ....then decide.

What more can you ad that Ive somehow missed .

all the best.markj

Reply to
mark

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