Honeywell 3 Position Valve - Motor Problem?

[adriennebottomley]

I appreciate that this is a commonly discussed matter within this newsgroup, but the specific question we want to address/resolve is not one we can find the answer to here, so we thought we'd ask.

We have a Honeywell V4073A valve which seems to have died, so we've now removed the powerhead, and successfully rotated the spindle on the valve by about 10 degrees using a small adjustable wrench and minimal force (we didn't know whether it might have seized - we do live in a hard water area). As a consequence, we now have just HW (which is what we want for now, we don't want the radiators on too - before removing the powerhead, we could get HW + CH (not ideal in mid summer) by forcing the manual lever over to manual with a large matchstick!).

Now, with the powerhead off, and the spindle manually rotated, we have just HW. We now have to decide whether to a) buy a whole new valve and drain the system b) buy a new powerhead and refit it on the valve (perhaps only to find that this too burns out because the spindle requires too much force for the motor?) or c) to just buy a new motor (I believe the latter can be bought for between =A310-=A320 depending on whether one buys a generic on from Screwfix, or a Honeywell original).

The old powerhead (still connected to the mains) is now resting in a non conductive bowl on the airing cupboard floor, essentially to we could check to see whether the motor's ever active. We have tried selecting CH only with the thermostat turned up, but nothing ever stirs in the powerhead (could be faulty/worn microswitches?). We have also tried watching when the HW is selected, but nothing stirs (we reckoned from the tech sheet that power may only flow when CH is called for). We have tried both HW + CH too. Prima facie, it looks dead.

At this stage we just want some advice as to whether it is would be wiser to go for an entirely new powerhead, or just the motor, and how we might go about testing the integrity/functionality of the present powerhead in order to decide. We'd also like some advice about how easily the spindle, which sticks up out of the valve, *should* turn. We've read elsewhere that it might turn with just "finger pressure", however, without a torque wrench and some idea of what Newtons are required, we don't know how much force is normal so don't know if the valve may be stiff. This, no doubt is why one usually calls in the professionals I guess!

Advice gratefully received.

[Set Square]

There are several checks you can do to determine the state of the valve. [You may have done some of this already]. Select CH (only) at the programmer and turn the room stat turned up to max. If the valve doesn't open with the actuator attached, remove the actuator from the valve and check whether it then motors to the CH position. If it does, the wet part of the valve is too stiff for the motor to turn - and will need to be freed or replaced. If the actuator *still* doesn't move, you've either got a duff motor or a wiring fault.

Another thing you can do is to turn the electrics off at the FCU which feeds the system (not the programmer) and then move the valve to the manual position with the lever. If, when you let go of the lever, the spring return moves the valve back to the HW position, you know that the wet part *isn't* seized. [Incidentally, if the wet part seizes, the motor shouldn't burn out - it's designed to run stalled, and is powered, but stationary, in the mid and CH positions].

My guess is that you've got a failed synchron motor in the actuator. What I would do in these circumstances is to buy a new actuator to get it all working again *and* buy a new motor and repair the old actuator as a spare. Provided Screwfix say that their motor fits your valve, buy that if it's cheaper than the Honeywell-branded one - they are probably identical anyway!

[Harry Bloomfield]

It happens that Set Square formulated :

I concur with all of that.

You should be almost able to turn the valve with finger tips, if you have a really good strong grip. So very light pressure to turn it with pliers/small adjustable is fine.

[ocidental]

AFAIK a mid position valve should natuarly return to its midposition. From what you say yours isnt so I'd say replace the whole thing.

[adriennebottomley]

Many thanks to everyone.

A few questions.

The spindle can be rotated with effort, but the key question seems to be "how much effort" is required to differentiated a "siezed" spindle in the wet part of the valve, from a normally functioning spindle. The last remark that it "should naturally return to its midposition" is confusing as it isn't clear whether the refferent here is to the spindle or the powerhead when on top of the spindle. At present we have the spindle exposed but rotated so we get just HW, and we have the powerhead on the floor.

What we need to confirm is whether the powerhead, detached from the spindle and valve, should show any life when the thermostat is turned up and CH selected at the programmer. What we may not have picked up on is the importance of testing the transition from no power at all to power on again (which means isolating the powerhead and programmer from the rest of the mains by switching off those fuses?).

Sorry to be vague here, but as things are, we still can't tell whether the primary fault might be with a semi-siezed spindle, or a faulty powerhead/motor. We naturally want to avoid having to replace the whole valve as this means getting someone in to drain the system as well as replacing the part.

Thanks again.

[Set Square]

Please don't post confusing rubbish like this when you clearly don't know what your talking about!

A mid-position valve is so called because it has a mid position where both CH and HW circuits are fed at the same time - rather than being a simple diverter valve which gives *either* HW *or* CH but *never* both at the same time.

With all power removed, the spring return on a mid-position valve will return it to the HW position. It requires *power* to move to - or remain at - the mid position.

[Set Square]

Ignore the post suggesting that the valve should automatically return to the mid position. That's rubbish, as explained in another of my posts.

You should have an FCU (Fused Connection Unit/Isolator Switch/Call it what you will) which enables you to remove *all* power from the heating system. Switch it OFF. [If you can't find it, switch *everything* off at the meter].

AIUI, you currently have the wet part of the valve in the HW position. When unpowered, the actuator should be in the *same* position. i.e. if you sit the actuator on top of the valve, the D-shaped slot should line up with the spindle without having to rotate anything.

Does it? If it does, take the actuator off and operate its lever. Looking at the underside, you should see the D-shaped slot move round to the mid position. Does it?

When you let go of the lever, the slot should move back to the HW position. Does it?

Now bolt the actuator onto the valve and again operate the lever to move the valve to the mid position. Then let go of the lever. The spring return should move the valve back to the HW postion. Does it? [If it *does* - the valve is OK and *not* seized].

Assuming you've answered Yes to everything so far, remove the actuator again, turn the power back on, and select CH with the room stat turned up. Watch the underside of the actuator to see whether anything moves. If it

*doesn't*, you've got a duff motor - or a wiring fault.

[ocidental]

When I had trouble with my Honywell 3 port valve I like you had the spindle exposed but with CH selected, but I had to have a mole wrench holding the spindle which together with a piece of wood wedged against the wall to forced it to stay in the CH position. If I wanted hot water I'd remove the wedged wood and it would without any actuator or any help from me, go into the midposition and I'd get some hot water from the cylinder because the path of least resistance is via the cylinder.

Your valve seems stickier than mine so in my opinion it would be more reliable if it was changed.

[Set Square]

The actuator has a relatively small motor, but operates the valve through a

*massive* gear reduction - and is thus able to produce quite a lot of torque at the spindle. The acid test is whether the spring return can move the valve back to the HW position with all power removed. If it can, the motor - provided it isn't duff - will have no difficulty in rotating the spindle to the mid or CH positions. [If in your other post you were trying to say that *your* valve gravitates to the mid position due to water flow on the paddle with the actuator *removed* you should have made that clear. That is quite different from moving to its "home" (HW) position with the actuator attached. Your valve sounds unusually floppy. Mine is quite a lot stiffer than that, but still works perfectly happily.]

[ocidental]

No it was nt, know it all, read my other post I was speaking from experience.

maybe you should ...

Actualy I regret the out of place language against a venerable poster and as you see I can resist that urge, but I stick with my opinion the OP should change the valve. This is the time of year they stick after the first time its been over to the CH side for 3 months or so.

[ocidental]

Ahh you have one too!

SS sorry about the tone of *that* reply.

cheers Old Floppy Paddle.

[Set Square]

Accepted.