Overheating Henry Vacuum Cleaner

[Vortex3]

Any Henry vacuum cleaner geeks out there?

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Today Henry # 1 stopped working. It was running very hot and under load and I assume some kind of thermal cut out "cut out". Went back 30 minutes later and it worked fine.

When investigating I found that even on "no load" (ie the motor assembly completely removed from bag and filter) the exhaust air was still surprisingly warm.

So I made a comparison with our other very much newer Henry (lets call him Henry # 2). On this one the exhaust is not so noticeably warm under the same circumstances.

So I investigated further.

Henry # 1 (old) states 850W motor and draws 4.45 Amps at idle.

Henry # 2 (new) states 1000W motor and draws 3.95 Amps at idle.

Methinks there's something wrong with Henry # 1....which seems to be converting about an Amp of supply current straight into heat!!!!

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Q1. Are these symptoms consistent with a simple-to-fix fault? (ie change the motor or similar)

Q2. If so is the motor easy to change (I assume so as spares are readily available).

....or should I just go to Homebase and buy a new one (currently on offer at £85) and keep the old for parts

Any opinions appreciated.

D

[R]

The motor assembly in the Henry range (And others from Nu-Matic) uses air drawn in through the hole in the motor base through curved fins within the rotor fan section to provide suction and motor cooling. Dust and dirt adheres to the fins causing slow airflow, reduced suction and motor overload. Hence your need to cool it down and the thermal trip to reset

*Usually* the fan housing is NOT able to be disassembled easily. You can soak the bottom section containing the "fan" in warm soapy water, agitating by gently shaking the unit by hand in the water/soap mix until the debris and silt is cleared. DO NOT ALLOW WATER INGRESS HIGHER THAN THE TOP OF THE FAN BASE. Flush with clean water only after cleaning prior to allowing to dry., DO NOT use compressed air to dry as this can distort the fins and lead to imbalance. IT IS ESSENTIAL that the unit is dry before re-use. DO NOT UNDER ANY CIRCUMSTANCES use the assembly until properly dry or the same result will happen, blocked fins.

Motors are available through Nu Matic

or some good hire shops.

(Ex Hire trade engineer looking after 150 of these extremely good, hard working units and their larger "brothers")

[Andrew Gabriel]

I'm not intimately familiar with Henrys (have used a couple which weren't mine and found them rather useless), but I assume it has a universal motor (i.e. with commutator and brushes).

These are rather inefficient and rely on a good airflow to remove the heat. If airflow is restricted (blocked filter, or coupled up to something which doesn't allow enough airflow), the motor can overheat and be permanently damaged in a way which generates more heat (don't assume a thermal cutout will do so before damage is done). Common damage is a shorted winding (most commonly on the armature, but can be a field winding), or a bearing which has gone stiff.

[R]

Your non familiarity is blatantly obvious as you know little about the product. The hire trade uses these units *because* of their reliability, spares availability, sturdiness and longevity I personally have 2 units *because* of these reasons and have also used frequently the "Wet-Vac" version twin motor unit which is suited to damp and flooded floor type environments.An extremely robust and tough unit.

Inefficiency during normal standard use is relatively insignificant in the case of the single motor units from Nu-Matic. The suction capability is as good as any modern cyclonic units, and is usually defeated by the user leaving out any filter or pre-filter from the unit in an attempt to increase suction. Missing out the bag also causes premature failure especially if the pre filter is missing also. Failure of the motor bearings is extremely rare in these units, and brush failure is found after hundreds of hours use in heavy industrial applications. Brush exchange is a simple job to undertake and unless the unit is used inappropriately in wet conditions the armatures rarely fail. Thermal cut-out, fuse failure or cable fatigue is usually the normal reason for complete unit failure, followed closely by the user using the unit for something it is not designed for. I have personally experienced a user using a simple Henry to remove bilge water from a boat hull. With the expected (After 3 mins) interesting electrical pyrotechnics ;-)

[Dave Starling]

Interestingly I too have two Henry machines. I rescued one from being dropped off at the local tip before the workers there spied it :-) Anyway, it works ok but suffers from the overheating that OP mentions. Its hardly worth having it repaired by a shop since they'll charge at least =A340 and this is uk.diy! I'm interested that R suggests soaking the bottom part of the machine to loosen dirt, but don't feel quite willing to risk it. If i start removing screws from the case, can I get to the same part so I can see what is being immersed?

Dave.

[Laurence Payne]

What IS your favoured sucking machine?

[The Medway Handyman]

Never come across a vacuum cleaner that didn't use a universal motor.

[Owain]

Noticed in a shop t'other day they now have Hetty (Henrietta) as well.

Owain

[The Medway Handyman]

Yup!

There is a TOL which will reset when it cools down. However its a warning that if you don't sort the problem the motor will burn out. TOL's on this sort of machine become more sensitive every time they operate & will soon fail in the 'off' mode.

The motors in Henrys are direct cooled e.g. the air being sucked up the hose is then blown over the motor to cool it down. Anything restricting the airflow, partly blocked hose, filter etc will cause excess heat.

Doddle. A kid could do it. Spares are common & plentifull, even patent parts are available.

is one source, but find exactly what motor you need & Google for prices, hundreds of places sell Numatic parts.

If you change the motor you effectively have a new machine, roughly half the cost.

[The Medway Handyman]

Numatic for vacs, Honda for anything with a petrol engine huh? Who did you work for?

[R]

Interestingly I too have two Henry machines. I rescued one from being dropped off at the local tip before the workers there spied it :-) Anyway, it works ok but suffers from the overheating that OP mentions. Its hardly worth having it repaired by a shop since they'll charge at least £40 and this is uk.diy! I'm interested that R suggests soaking the bottom part of the machine to loosen dirt, but don't feel quite willing to risk it. If i start removing screws from the case, can I get to the same part so I can see what is being immersed?

Dave,

On the motor case remove the power cord retaining screw clamp. Remove the 3 cross head screws in the bottom of the top section that houses the motor. Remove the top cover watching for the foam pad that will fall out usually. Detach the motor wires. Dunk the motor base itself in warm soapy water and agitate until you think it's clean. Repeat as there will still be a lot of crud in there. Leave to dry somewhere for a day or more after shaking vigorously to remove excess water. Reassemble.

[R]

Small independent in Eltham SE London.

You forgot Iseki or Yanmar for the diggers, dumpers and some screeders as well......

Oh................and.....................Belle 4/3 Mixers......

And Bosch 4, 5, 9 and 12" Angle grinders........

Makita battery units.

etc etc etc etc etc

[R]

[Bob Eager]

Are they all pink? All the Hettys I've seen have been...

[The Medway Handyman]

Andara?

[Andrew Gabriel]

You haven't given enough info to diagnose.

If the airway is blocked, the motor load is reduced because it's not doing anything, hence the motor speeds up, and power consumption drops.

If the motor is losing power internally (usually due to damage), the motor slows down, and power consumption increases.

In both cases, the motor can overheat, so that alone doesn't indicate the cause. The OP gave enough info to identify the latter (motor is losing power internally -- it could have started with overheating due to blocked airflow, but if so, it has gone past that to motor damage now). You haven't given enough info to identify which scenario applies.

If you momentarily block the airflow of a vacuum cleaner, you will hear it speed up as in the first case, except that if it is already blocked, it won't speed up as much as it will already been running faster than it should. If you are using a vacuum cleaner you're familiar with, this is a good test to do occasionally to check for blockage, to make sure you get the expected speed up if you block the airflow for a couple of seconds. If the speed up is less than normal, then it is probably already partially blocked, and that should be investigated. Don't rely on thermal trips to protect motors; a big problem with them is that when they trip, cooling stops instantly, but heat will still be working its way out from hot areas, and increase temperature of other parts and damage them during the time the motor is tripped out. (This is why when you overheat a drill motor, you should run it for a while at full speed no load to cool it, and not just stop using it, which is much more likely to wreck it.)

[Owain]

Yes, looked a bit like Henry had "come out"

Owain

[Vortex4]

OP Here........

Thanks for your help all.

I am inclined to think the motor is "borked" because of the high current usage even on no load

The overheating has been a sudden phenomenon.....though no boubt internal blockages could have contributed.

Since replacement is apparentluy simple I will pick up a new one in due course.....and decrud the fan while I am at it.

David

[R]

*ding* Give the boy a cigar.....

[Wingnuts]

replying to The Medway Handyman, Wingnuts wrote: Hi, I have a Henry NVR200 which is over heating.

I've stripped it down and cleaned it as best I can.. The brushed have about

15mm left on them and the fans underneath the motor were pretty clean but I soaked them in warm soapy water nonetheless and then used a bottle brush to get in-between them. I then attached a drill to the nut and ensuring the correct direction I spun it up to dry out any moisture that remained, if any.

The lack of obvious fluff and dirt and that it was pretty clean in the first place bothered me; I was expecting something more significant to explain the tripping of the thermal cut-out. I cleaned everything and re-assembled Henry.

There was a noticeable improvement in the suction and the motor didn't trip out...... until just now.

So, before I strip it down again, could the thermal cut-out be faulty? I'm guessing it's unlikely as Henry runs for a short time before it cuts out, then it starts up again. I'm guessing this is due to the thermal cut-out cooling slightly etc etc.

Does anyone have any advise on troubleshooting the actual cause or a process of elimination I should follow?

I know this post is over 10 years old, but I have faith in you lot :)

Thanks in advance,