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Plumberpro, Plumber
Category: Plumbing
Satisfied Customers: 634
Experience:  Heating and plumbing answers. 20 years experience
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I have an S system that has experienced control problems for

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I have an S system that has experienced control problems for some time. The system is microbore over three floors with TRV installed on upper floors. Additional to the CH & HW actuators I have a 4035 two port actuator at the hw cylinder inlet. I have replaced the actuator to the CH with ML7300A1004. This provides the F3 code. I then replaced the original CH actuator and moved the new actuator to the HW with the same F3 code result. Before making these changes I had CH & HW which I had to reset after reaching temperature by removing and restoring power. I have removed the head of the 4032 as there seemed to be mechanical resistance in the gearing and spring return of the motor sprocket and I have removed the cable from the terminal block. I now intend replacing the 4032 but am bemused by the situation. Any advise would be appreciated
Plumberpro :

Hi , did you use an s plan wiring guide?

Plumberpro :

Or is it smartfit

Customer: No, I am a home owner with an as supplied system. The wiring seems to be broadly as detailed as far as I can see but it is complicated by the addition of the 4042 actuator on the tank inlet pipe. I am not clear about the function or need for this although I read somewhere that this might be to provide protection where TRV are installed although these are not fitted to all radiators
Customer: Sorry Smartfit S plan
Plumberpro :

Hi , I can't understand why you would need two actuators on the hot water circuit. Have I read right?

Plumberpro :

You only need one for heating( or more depending on size of house) , and one for hot water.. I would remove the additional one. Is it wired up?

Customer: Yes. The Honeywell Smartfit actuator valves control CH & HW and their function and location in relation the the pump and pipe work seem fine. The normal 4042 actuator with the auto/manual lever seems superfluous but it has been in circuit since I bought the house 13 years ago.
Plumberpro :

Ok , it would be worth removing it and replacing with pipe as it may be causing problems with flow.

Customer: i initially removed the head unit in case the motor had failed and have subsequently removed the wiring, leaving the base unit with the valve ball in the open position. I still have the F3 short circuit message
Plumberpro :

Ok , is f3 a flow/ fault

Plumberpro :

Nit sure of your boiler , but I take it the f3 code was a flow/ overheating error?

Customer: no its a short circuit fault on the CH actuator. The Honeywell manual indicates actions to take to the point of changing the actuator which I have done.
Plumberpro :

Ok , did changing the CH actuator work?. I wonder if it could be more a fault with the control unit

Customer: Having moved the actuators around with as many permutations as I can with three units available there seems no logic to the continuing failure.
Plumberpro :

Hi .it is a bit strange. Let me check with Honeywell and get back with you . I take it that fault code comes up on the programmer digital display?

Customer: I have looked at that and cannot see anything to indicate a failure. Is it common for these solid state units to fail
Plumberpro :

To be honest smartfit arnt really used much , especially by the trade,. I've not come across that issue before. But everything fails eventually

Customer: Yes. As sonn as returning the power I get the F3 for about 2seconds, followed very quickly by the usual timer display for about 2seconds and then F3 again
Plumberpro :

Ok.does the heating and hot water still work afterwards?

Customer: I think I now appreciate that. I tried to get BG to take me on for a service package about 10 years ago and they weren't very happy with Smartfit
Plumberpro :

I know there were few thing problems with bit at first

Plumberpro :

Teething , sorry ,

Plumberpro :

So when the cerror comes up , does that mean no hot water and heating?

Customer: Yes. No functioning system at all. This is part of the frustration. If I have a call for heating and a fault on the CH actuator I can understand that but I don't understand why if I call for HW I still get the F3 and it stops everything
Plumberpro :

On phone to Honeywell technical. Could be a while . just want to see if they shed some light on it will get back to you soon as

Customer: Thanks for your efforts so far
Plumberpro :

Your welcome , have been on hold to Honeywell tech for a while . might need to call tomorrow as this is the time heating engineers start panicking and calling them

Customer: Ok, *****@******.***
Plumberpro :

Put hash before or it won't come up. I will have to call them tomorrow, its been 40 mins and no luck .

Customer: Eventually changed the wall unit with no improvement so changed the base unit which solved the problem. Contacted Honeywell Service who were no help at all. Trial and error approach solved the problem at some cost albeit that this was significantly less than call out charges and a heating engineer that probably had little experience of the Honeywell Smartfit System. I now have some spares that I will hold just in case or sell on eBay. Not a comfortable time but a useful learning process for the future.
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