DIY Doctor

replacing vailliant boiler

Postby tommyknocker » Mon Oct 15, 2007 8:52 am

Hi I would be grateful for some advise, I have a Valli ant combi boiler, 2 gas fires and a cooking hob all run off 15mm pipe, there is no problem with any of these the boiler is 14 metres from gas metre this being the longest pipe run, loads of elbows and about 5 tees but I have read some were that the pipe will have to be replaced because of the pressure drop will be required to be 1mb, the combi is due for replacement when I get the money together, also I have a Honeywell T6650A programmer ( all this stuff is approx 17 years old) which is playing up can anybody please recommend a programmer for CH only which I can straight swop, my regards Rob
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Simply Build It

Postby Perry525 » Mon Oct 15, 2007 7:46 pm

Your heading should be. Find a replacement for my controller?
However, the Honeywell T6650A is a very sophisticated and able programmer that is possibly over qualified for the job it does.
Do you really use its full programming capability?
I would guess that a far simpler programmer will do the trick?
By the way, you say its playing up! Have you checked the batteries recently?
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Postby tommyknocker » Tue Oct 16, 2007 7:42 am

Thinks for the reply Perry, yes checked the batteries and they are ok, my questions was in two parts rely, I was asking because I have no problems with the combi boiler, gas fires, and hob being run off 15mm pipe would I be able just to get a boiler to plug and play as it were or will I have to increase the supply pipe to 22mm I am going to get someone into do the boiler anyway but it would be nice to have an idea what to expect. The programmer was working ok until I tightened a lose wire in it, and now it will only work with the temp showing at 32 degrees, my regards Rob
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Postby htg engineer » Tue Oct 16, 2007 4:22 pm

The gas supply will have to be increased to at least 22mm.

Calculations as to how long the pipes are, the number of bends and what appliances are connected will have to be taken into consideration by the CORGI registered installer.

As for the timer/programmer, if your getting a new boiler why not get an integral timer ?
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Postby The Heating Doctor » Tue Oct 16, 2007 6:41 pm

I would suggest that as you are looking for a combi then the gas supply must be increased to a 22mm supply, your CORGI registerd engineer should be able to tell you that and perform the alterations. There are a couple of Vaillant options available to you as far as controls go, from a plug in 24 hour mechanical clock which goes in the boiler facia to a wire free programable room thermostat. The stats receiver plugs in to the boiler facia where the clock would have gone and the sender would be placed in the position in the house normally reserved for the room stat. The sender is a 7 day programmer with temperature options through out the day. Check out the Vaillant web site for full details.
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