Will These Changes Make My System An S Plan?

[3500P5BV8]

My old heating system (Concord WRS boiler) needs updating to S plan. At present, the 2 port valve only controls the heating. If a new 2 port valve was added where shown, would this be the right place?

I think I need a bypass, is between the cylinder primaries the right place?

In the system's current layout, if just the boiler was replaced (no other changes), would it conform to regs?

(NB Feed and vent pipes not shown, they are above the boiler)

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• 3500P5BV8
• 24 Jan 2010
• 3

 

[D_Hailsham]

That won't work at all. The bypass is in the wrong position. Here is a revised diagram:

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• D_Hailsham
• 25 Jan 2010
• 1

I see that the feed and returns are shown combined. On most pumped/gravity systems there are separate feed and returns for CH and HW. Does the diagram show the existing or proposed?

You have not shown the cold feed and vent pipe for the heating. Do they have a direct path to the boiler without passing through either valve or the pump en route? This is important.

Having the pump in the return can cause problems, if you can have it in the flow it would be better. Here is the "standard" S plan configuration:

View media item 71

 

[3500P5BV8]

Thanks for your reply. Yes, the bypass would make more sense there. Two more questions;

If the system wasn't altered at all, and only the boiler was replaced for a new one, would it be within regs?

Which type of bypass is best, a standard one, or a differental bypass? What's the difference?

 

[twgas]

The bypass is in the wrong position

Am I missing something but why would the by-pass be no good in the first picture?

Agree with the pump comment.

If the system wasn't altered at all, and only the boiler was replaced for a new one, would it be within regs?

No, there should be, on both HW and CH, an interlock to control the boiler.

Which type of bypass is best

Automatic

 

[D_Hailsham]

If the system wasn't altered at all, and only the boiler was replaced for a new one, would it be within regs?

No, it has to be converted to fully pumped.

Which type of bypass is best, a standard one, or a differential bypass? What's the difference?

When you say "differential", do you mean an automatic bypass? If so, any bypass fitted must be an automatic one. A bypass is only required if the boiler manufacturer specifies one. Some boiler have the bypass built in.

The old method of having a gate valve in the bypass circuit is no longer acceptable as there is a continuous flow through the bypass, which reduces the system efficiency.

 

[3500P5BV8]

If the system wasn't altered at all, and only the boiler was replaced for a new one, would it be within regs?

No, it has to be converted to fully pumped.

.

The systen is fully pumped. Its in a bungalow, cylinder same level as boiler. There is no stat on the cylinder. When the heating is on, the cylinder also gets heat.

Is this within regs?

Also these are the 2 different types of bypass;

Auto

http://www.screwfix.com/prods/34127...ols/Honeywell-Straight-Auto-Bypass-Valve-22mm

Differential


http://www.screwfix.com/prods/98894/Plumbing/Radiator-Valves/Differential-Bypass-Valve

What's the difference?

 

[D_Hailsham]

The systemn is fully pumped. Its in a bungalow, cylinder same level as boiler. There is no stat on the cylinder. When the heating is on, the cylinder also gets heat.

Is this within regs?

Sorry, I thought you had a pumped heating gravity HW which you wanted to convert to a fully pumped. If you want to comply with regs you need to install a cylinder stat and motorized valve in the cylinder circuit

Also these are the 2 different types of bypass;

Auto and Differential

What's the difference?

Nothing, just different names for the same thing.

 

[matt1e]

The bypass is in the wrong position

Am I missing something but why would the by-pass be no good in the first picture?

your missing nothing tw!
it will work exactly the same as in the updated pic

I agree with everything else though

Matt

 

[twgas]

The bypass is in the wrong position

Am I missing something but why would the by-pass be no good in the first picture?

your missing nothing tw!
it will work exactly the same as in the updated pic

I agree with everything else though

Matt

Cheers for that, thought the age was catching up on me for a bit

 

[3500P5BV8]

Thanks for your replies. Much appreciated. Looks like I need to get busy to save loads of gas.

One last question. My system is similar to a C Plan, except its fully pumped. What plan is it , does it have a name?

 

[twgas]

mucho cheapo plan.