randall 4033 problem !!

MURPHTEK · 9 Mar 2007

anybody help this is doing my head in ? i got a randall 4033 programmer on a y plan sytem with an ideal mexico boiler and i cant have just heating i have to put the hot water on for the pump to kick in ( is this normal ?) i have changed the 3 port valve and tested the voltage on both outputs for hw and ch on the timer and they both seem to be working fine. my understanding is that the whole point of a 3 port is that you can have either hw or ch not that you have to put both on, and once the hw is heated up the ch carrys on, otherwise whats the point in having such a simple timer with seperate hw and ch on off switches. the one thing is that i aint got is a room stat, thats just been bypassed in the connector block. had an sparks look at the wiring and he seems to think that its all wired fine and it is something to do with the plumbing "BUT WHAT"? "help"!!!!!!!!!!

gas4you · 9 Mar 2007

Sounds like a wiring fault in how the 3 port valve has been wired, or maybe the cyl stat.

How much do you trust your sparks? A lot of them, even though they may be good at their job, do not take on or understand heating system wiring

pannierstan · 9 Mar 2007

You say you have a three port valve but thats not to say it is a mid-position valve.

Neither is the system forced to be wired wrong. Its probably the case that because that clock does not have a heating only facility that they havent bothered wiring in the heating only wires into the system.

Get a decent programmer and a decent corgi as he should be able to wire it in and or tell you what is missing/wrong.

Stan

MURPHTEK · 10 Mar 2007

definatly a mid pos valve, its a honeywell sundial y plan V4073. Electrician is my wifes uncle and one of my best freinds,he is also nappit registered so i do trust him but you are right he has not really got involved in heating wiring , but after a few lengthy phone calls he has got back to me with the outcome that there was nothing wrong with the system in the first place and that your not suppose to have just ch and why would ya ? when if ya ch is on you might as well save money by heating the water at the same time, and in the same sense in the summer you only want hot water but no heating. this is why you can only have hw on its own but if ya want heating then hw has to be on for economical reasons. all sounds great !! but is this right????

gas4you · 10 Mar 2007

The 4073 is a 3 way valve that if wired correctly will give

1) ch only
2) hw only
3) both together

i suggest with respect that he may be very good sparky but does not understand heating system wiring

pannierstan · 10 Mar 2007

MURPHTEK said:
this is why you can only have hw on its own but if ya want heating then hw has to be on for economical reasons. all sounds great !! but is this right????

Unfortunatly he is definatly wrong. Economy comes from being able to heat either H/W or C/H individually.
Its not a fault of the system you have, just that it needs wiring with a new programmer so that you can have them on individually.

The main reason for most systems not having a heating only selection is that the DHW OFF live is missing from the clock.

You can fix it and it will definatly be worth it! However you need to get the roomstat sorted aswell or you are going to see some pretty hefty gas bills.

Stan

MURPHTEK · 11 Mar 2007

thanks for ya replys boys but god has it been a tuff couple of days. this whole problem has turned into a mass debate as my electrician like myself wants to understand how this whole system works and someone threw a spanner in the works by insisting that it was impossible for a 3 way valve to allow ch water to flow on its own without it passing through the hw side at the same time???? he said you could have hw on its own but because of the way the valve works it was impossible to have the ch port open on its own.and if i wanted to have control of ch and hw seperatly i would have to have an s plan which incorporates a different valve for each circuit. now i really didn't know what to believe. the thing is if it is right then i will just leave it as it is and think nothing more of it but if it can be sorted then i will call out a heating engineer to put it right. any of you live in the hayes ,middx area ??

gas4you · 11 Mar 2007

I can assure you that if it is a proper 3 port mid position valve it can give options that I listed in previous post. Your latest 'adviser' is completely wrong

If it was an 'old fashioned' divertor valve then it would only give heating or hot water.

Go to this address (http://content.honeywell.com/uk/homes/Technical/ST7X2/ST7100.pdf) for a sample Honeywell wiring diagram for a 'Y' plan, but substitute your programmer for the 7100.

I think pannierstan is correct in that the DHW off has not been connected properly

Please get in an electrician who understands Y plan wiring and what is happening when controls are being activated etc.

ollski · 11 Mar 2007

We have loads and loads of 20 year old systems round here on mid position valves theat have been wired up so that they will only call for heating if both heat and water are switched on at the clock. You could change them over and rewire to a correct y plan system if you cared enough but they are only topping up your hot water to the stat temp whenever the heating is on.

MURPHTEK · 11 Mar 2007

nice one fellas. really appreciate the help you have been great

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randall 4033 problem !!

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