Boiler control question - updating?

[Sirbendy]

The property we're about to buy has a Baxi bermuda (unknown model) backboiler. The wall controls consist of a 1 day water/heating timer (Forgotten model, but electronic),and a "twist knob" thoneywell thermostat.

I want to change the controller for a 7 day one anyway, but thenl I chanced upon the Honeywell CM 67 (and newer ones) that say they replace the turn 'stat and offer timed heating and different comfort levels on a programme etc.

This sounds like EXACTLY what I want. My question is, can it be fitted on a backboiler system?

If so, is it simple enough to dismount the turn dial one and replace with this unit, and what do I then do with the existing basic hot water/ch programmer?

Any advice gratefully received..

 

[ollski]

You can, but sometimes these randall clocks act as the complete wiring centre so a reasonable amount of rewiring required.

 

[Sirbendy]

Ah! Found the programmer it already has - it's a Honeywell ST699. 24 hour job, basic. Don't really want this, as we don't have a fixed "every day" routine.

There's a tank 'stat that looks to be an L641A, and the roomstat is identical in appearance to a T6360B. As I say, it all goes to run a Baxi backboiler, either a 45/3, 57/3, 45/4 or 57/4...not sure quite which until we get in there.

"Wiring Center"...what is that, in heating system terms?

My understanding is that the ST699 is the "brains" (such as it is) that flicks a relay over to say "fire the burners", based on time set, and 2 inputs from the roomstat and tankstat that just open and close depending on temperature. I'm guessing it starts the pump as well, and sets a valve for either heating or hot tank flow..correct?

So, would that make the ST699 a wiring centre?

I wish I'd taken a photo of the pipework..if it has heat/hot water controls, I'm guessing it has a 3 way valve. I was under the impression that a bermuda BBU was a gravity hot water system job...therefore I would have thought a seperate unpumped pipe system for the hot water versus rads..?

It's all new to me, although being a computer tech and electronics tinkerer, the controls and theory seem simple enough..!

My end goal is to update the controls to something "intelligent" now (Like the CM67 etc) to get an adaptive system that can be tailored to the family needs, and then when the bermuda finally croaks, get a new boiler fitted (either a HE BBU or other), and keep the controls.

Would that be a possibility? And if the CM67 wouldn't fill those needs, can anyone suggest what might?

(I should add, wired is fine. CM901 or older equivalent would be about what I'm looking towards..something a bit intelligent, that I can put in place of that manual roomstat. Hot water is fine to heat once a day on the old ST699, but house radiators I want to be a bit more flexible!)

 

[D_Hailsham]

A wiring centre is a junction box about 6" x 8", usually found near the pump and hot water cylinder. All controls connect to it.

If you have a tank stat, you will either have a fully pumped system or a C-Plan system, which is a modified pumped heating/gravity HW system.

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Are there any motorized valves (see pics below) if so how many and which make/models?

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The ST699 just controls the times when you can have heating/hot water. starting the pump and setting the valve is done by the appropriate thermostat

I wish I'd taken a photo of the pipework..if it has heat/hot water controls, I'm guessing it has a 3 way valve.

A pic would be helpful, if you can get one

I was under the impression that a bermuda BBU was a gravity hot water system job...therefore I would have thought a seperate unpumped pipe system for the hot water versus rads..?

It could still be a gravity HW system; that's why the number and type of valves is important

My end goal is to update the controls to something "intelligent" now (Like the CM67 etc) to get an adaptive system that can be tailored to the family needs, and then when the bermuda finally croaks, get a new boiler fitted (either a HE BBU or other), and keep the controls.

No reason why you shouldn't do that.

My son had a fully pumped baxi back boiler system with basic controls so five years ago I installed an Honeywell CM67NG wireless stat for the CH and a 7-day single channel timer for the HW. Just over a year ago the boiler gave up and a modern condensing OV boiler was installed. The fitter just had to wire it straight into the wiring centre.

The CM67 has been replaced the current versions are the CM907 (wired 7 day) or CM927 (wireless 7 day)

Provided you are happy with the same HW times every day, the ST699 will do. The only disadvantage I can think of is that it does not have a one hour boost button. You can press the Change button if you want HW outside the normal times, but you have to remember to press it again when no longer required.

 

[Sirbendy]

Cheers - we're exchanging contracts today, keys hopefully on Friday, moving saturday morn, so pictures can be got then.

It's an odd setup...there's a switch (lightswitch!) in the kitchen, and one in the airing cupboard marked "Heating and Hot Water"....not sure quite what that's about...on/off for the Baxi maybe? There's an immersion in the tank as well, but I'd have thought the Baxi would be a "permanently on" boiler, as all are..

I'll be having a good prod at it and a read through the manuals...I have the sellers mobile number too, so I can always call them up and ask, I suppose..heh.

I can see me asking quite a few questions on here (you poor, poor people).

Hot water I'm happy with..1/2 times a day will do fine. It's just used for bathing our little person. There's an electric shower and dishwasher for the rest. Only the heating system will annoy me being basic, I think!

 

[D_Hailsham]

we're exchanging contracts today, keys hopefully on Friday, moving saturday morn

Four days from exchange to completion? That's quick - almost impossible! How have you achieved it??

It's cheaper to heat the water using gas than using electricity, though if you have an electric shower you might as well use it.

Your system sounds very basic. When you are in, get all the info you can, including pics, and post into this topic.

 

[Sirbendy]

Oh yes, it's been quick throughout...we put in the offer on the place 2nd week of april. Today wasn't actually exchange as it turns out, it was all the paperwork, signing etc. Completion and Exchange is happening on Friday! Heh.

Sellers solicitors and ours know each other well - this property has been on the market for a while too, and the sellers want to sell. It's been vacant for months.

Looking at all the paperwork I see here now, the boiler was installed in '97, with the Double Glazing. I'm going to assume it was replacing an existing bermuda - can't think of any other reason to use one than to replace an existing unit, and the firefront looks like a 70's throwback...

So in itself the boiler may be more modern than I first suspected..and it passed it's last annual check in Dec 2010 with flying colours. Feeling a bit less alarmed about it now.

When I'm in, there will be pictures. As much detail as I can find.. I want this system to be adaptive and "tech"esque..now we own and not rent, it's time to unleash my inner geek and indulge in some nice clean upgrading fun.

I've already bought a cheapie old-generation Roomba to unleash on the floors downstairs, to try and lower the missus' blood pressure..heh.

I blame computers...working with them all day I find them dull..but automation and things like that I find fascinating..

 

[ChrisR]

1997 almost certainly means fully pumped so you can just change the room stat for a programmable one, leave the CH on 24hrs on the 699.

 

[Sirbendy]

Right, we've been in the house since Saturday.

Now, I can link the pics once I've got them up, but there's a T shaped valve with a Grundfos pump on the "AB" single pipe leading to it. One end of the T goes to the hot coil in the cylinder, one to a pipe that I would assume is the CH system.

So, am I right in saying that's a 3 port valve and the DHW/CH is fully pumped?

After much purging of air from the appliances before I could persuade them to light, I could NOT get the Bermuda to stay lit. The pilot would come on, hold in the grey button for 30 seconds to 2 minutes (yes, I was trying longer just in case!)..as soon as I released it gently, the pilot would die out.

So, "stuff it" thought I. "Lets go and look at the airing cupboard". There's a 10 way double-socket sized box that I'm guessing is the "wiring centre"(?)...9 ways in it, number 10 has been chopped off the chocblock.

I clicked on the Hot Water on the ST699..."WhirWhirWHIRRWhirr"...something sounds like death. It's the 3 way valve sounding very rough. Flicked the Heating switch to on, even more comical noise as it came back.

Oh well, thought I...it moves, so..that's fine.

Pump fired up each time something was set to "on", nice and quiet.

Then the missus said "oh, what does this switch do?"...it's the "1/0" switch on the side of the T6360C 'stat. She flicked it.."pop". System goes dead.

It's blown the 3 amp fuse in the airing cupboard. Set the switch back to "1", popped in a new fuse, all good. Except now, as soon as you select "CH on", it pops. Hot water is OK - pump runs.

Left it and got on with moving in.

Day 2, now whatever you select on the programmer (DHW or CH on), fuse immediately pops.

I have a gas guy coming to look at it all anyway, but any suggestions as to what it may be? I can move the 3 port with the lever - motor sounds rough, but it all moves.

From what I can see, the "1/0" switch just flicks the 'stat in and out of circuit - is this right? If so, I can't see why that'd pop anything. Possibly co-incidental and it's more an issue with the valve or pump?

My Drayton Digistat +3 turned up to replace the T6360C yesterday - after studying the posts on here, honeywell wiring plans, 'stat wiring etc, I can see the following:

Current T6360C has 3 wires. Red, Blue and Yellow. Terminal 2 is Blue, 3 is Yellow, 1 is Red. Earth is floating unattached, but it's double-insulated, so in theory unneeded anyway.

From what I can see, 1 (red) is live in, 2 (blue) is neutral, 3 (yellow) is load in theory, and the 'stat has the "anticipator" that needs the neutral.

So...from this site, it seems I should disconnect the neutral wire and make it safe (heat shrink sleeving OK for this?), then connect 1 and 3 (live and load) to the digistat terminals C and On respectively . Correct?

It's the battery powered Digistat +3 by the way.

Apologies for the length!

 

[D_Hailsham]

Now, I can link the pics once I've got them up, but there's a T shaped valve with a Grundfos pump on the "AB" single pipe leading to it. One end of the T goes to the hot coil in the cylinder, one to a pipe that I would assume is the CH system.

So, am I right in saying that's a 3 port valve and the DHW/CH is fully pumped?

Yes. Make and model no of valve would be helpful.

After much purging of air from the appliances before I could persuade them to light, I could NOT get the Bermuda to stay lit. The pilot would come on, hold in the grey button for 30 seconds to 2 minutes (yes, I was trying longer just in case!)..as soon as I released it gently, the pilot would die out.

Are you talking about purging air from the radiators?

Was the gas turned off at the meter? If so you may need a Gassafe registered guy to purge the air in the pipe from meter to boiler (and other gas appliances).

There's a 10 way double-socket sized box that I'm guessing is the "wiring centre"(?)...9 ways in it, number 10 has been chopped off the chocblock.

Yes, thats the wiring centre.

I clicked on the Hot Water on the ST699 ... "WhirWhirWHIRRWhirr" ... something sounds like death. It's the 3 way valve sounding very rough.

Turn the complete system off at the main switch and set programmer to HW and CH Off. This "resets" the valve (a bit like Ctrl+Alt+Del - I was in IT for years. )

Now try again turning only the HW on. You shouldn't hear the valve move as it is not used for HW, only for when CH is called (with or without HW).

Can you check that the valve is the correct way round - Port A to rads, Port B to Hot Water cylinder.

Can we have a pics please of mystery switch on the side of the T6360?
Also a pic of the wiring centre (lid off!), with the wires identified if possible.

I can move the 3 port with the lever - motor sounds rough, but it all moves.

It does sound rough as you are trying to open the valve against a spring

From what I can see, the "1/0" switch just flicks the 'stat in and out of circuit - is this right?

Can't see the point of that. Perhaps it's a throwback to the days when the system was semi-gravity, i.e pumped heating and gravity HW. The Switch could have just turned the pump off so you just got Hot water in the summer. If so, whoever upgraded to fully pumped should have dispensed with it.

You are correct about wiring the Digistat. Just make the Blue neutral safe - a single chock block is the favourite but heat shrink sleeving should be OK for this. Then connect Red and Yellow to the digistat terminals C and On respectively.

I think you should sort out the blowing fuses problem and the purpose of the switch before installing the Digistat. You don't want to blow it up the first time you turn on!!

 

[Sirbendy]

I can try and get the data of the valve, but where would I find it?

Re: Air - no, it was in the supply lines. Gas was off at the valve, when I threw the lever there was a very audible "whoosh", and it was a case of open all windows, mains off, gas rings on until gas was smelled. Definitely lots of air in there..

Boiler was the same - mains off, use the manual gas valve push button, wait for it to clear, mains on, push and hit igniter.

The cooker wouldn't fire at all until I did that, then the flames were yellow to start, then settled to a nice blue. Ditto the Bermuda..yellow flames for 5 seconds or so, then settled to blue. Assuming it was the last of the air in the system working the way out.

No different to purging an injection system on a car..heh.

The house has been vacant for months..spa bath jets spat gunk out, loo bowl had grey water in it etc. Not surprised about air in the gas line!

I'll try the valve reset tonight...

I also couldn't see the point of the "1/0" switch on the T6360C..but it definitely is shown as an "on/off"..

http://www.honeywell.com.pl/pdf/automatyka_domow/termostaty/T6360.pdf

There's a diagram on that PDF showing the internal schematic, and it definitely shows it as a secondary "breaker" of the thermostat output signal..heh. Odd thing.

I have a horrible feeling the pump may be going...the gas chap should be here this week, and we will hopefully get that running again. Currently using the immersion for hot water, and the house is well insulated (digistat has been showing 19 degrees this morning, no heating since the last people moved out..not bad!).

 

[D_Hailsham]

I can try and get the data of the valve, but where would I find it?

There should be something on the valve. If not a pic will do. Also the number of wires in the valve cable will help.

I didn't realize that you were talking about a switch actually on the thermostat.

Your link to Honeywell in Poland fell over, but I found it in their main Europe site.

You said earlier that T1 is red (assumed live) T2 is blue (assumed Neutral) and T3 Is Yellow (assumed Switched live).

If that is correct, when you close the switch you will immediuiately short live to Neutral - look at the Honeywell diagram for the inside of the stat. The T6360C does not have an anticipator, so no need for a neutral.

You need to use a meter to check which wire is the live and which the switched live.

 

[Sirbendy]

Pic of 3 way valve...

http://imageshack.us/photo/my-images/812/dsc00282m.jpg/

Pic of wiring centre (messy)

http://imageshack.us/photo/my-images/97/dsc00295lc.jpg/

pic of 'stat showing 1/2/3 wiring

http://imageshack.us/photo/my-images/200/dsc00302rn.jpg/

 

[D_Hailsham]

Pic of 3 way valve

I think that's an "A" on the nearer port, which appears to go to the rads. So that's OK

Pic of wiring centre (messy)

You don't say!!!

pic of 'stat showing 1/2/3 wiring

And here's a pic showing the connections. As you can see 1 and 2 are joined together, after the switch. So connecting Line to one and Neutral to the other will just blow the fuse when the switch is closed. If you connect Live to 1 and Switched Live to 3, the internal switch is bypassed.

The T6360 is intended for aircon systems.

T6360C Wiring

• D_Hailsham
• 7 Jun 2011
• 1

T6360C with On/Off switch and no anticipator.

Replacing it with the Digistat will overcome your problems, but do make sure you know what each wire does: Live - Neutral (not required) - Switched Live.

 

[Sirbendy]

I see....

Odd setup!

Did a full power off last night, set the ST699 to "Off" for heating and DHW, "Auto" on the mode switch.

Main switch back on, new 3amp fuse in the supply box in the cupboard. Not a spark of life in the ST699. Fuse gone straight off.

Now, with the ST699 on "off" for both channels, nothing should be doing anything surely...?

I wonder if that switch on the T6360 has jammed or similar..that was the only thing that was altered when it first went pop.

If I stocked up on 3 amp fuses (argh), would it be worth me turning the power off totally, "de-wiring" the 'stat and trying without it to see if the fuse goes?