Regular to System boiler conversion?

330d

Currently at my house the hot water setup is a cold water storage tank in the loft, regular boiler and a hot water cylinder.

The current boiler needs replacing and looking to replace it with a like for like regular boiler.

But in the future we may remove the cold water storage tank in the loft, if we did would the regular boiler still work? Can it simply run off the incoming cold water mains? I really dont want to be buying a System boiler.

I read somewhere I would also need an expansion vessel as this is the main difference between the Regular and System boiler. Is this correct?

Jeepers_Creepers

That's the gist of it. But...

A 'regular', 'conventional' boiler means it's 'vented' which means that it needs a SMALL expansion (F&E) tank in the loft. So, do you ALSO have one of these at the moment, or is there ONLY ONE LARGE tank up there (the 'CWS' - cold water storage)?

Or, does your existing boiler have a pressure gauge? If so, it's a 'system' boiler and not 'conventional' vented.

So, first thing to answer - does your boiler have a pressure gauge, or, does it have a small F&E tank in the loft?

That's one issue. That concerns the actual boiler.

The other - quite separate - issue is the LARGE water tank in the loft, and that it feeds the hot cylinder. That means your DHW (domestic hot water) system is 'vented', or 'gravity'. Ie, the flow from your hot taps ultimately comes from that cold tank in t'loft.

So, that's two different things we are talking about - the type of boiler, and the type of DHW.

CAN YOU CLARIFY - YOU ARE NOT CONSIDERING CHANGING TO A COMBI BOILER? Ie, one that instantly heats your hot water on demand? One that DOESN'T have a hot cylinder?

Ok, assuming you are NOT going 'combi' at any point, when you come to replace your existing boiler, I'd say you definitely DO want to go 'system'. Why? Because it's sealed, and you then lose that SMALL tank in the loft. You'd be nuts to remain 'vented' and keep that small tank.

That's one point. The new 'system' boiler will behave exactly like the existing boiler - it'll still heat up your hot cylinder. If, in the future, you then decide to remove the LARGE cold tank in the loft, then you'll need a NEW hot cylinder, one that is now fed directly from the mains supply - ie it's 'unvented' or 'pressurised'. That won't affect the boiler - the boiler will happily heat up whichever type of hot cylinder you have, vented or unvented (loft tank or mains-fed).

Does that make sense?

Sooooo, do you have a wee tank in the loft for the boiler? Cool. When you replace your boiler, deffo get rid of that and go 'system'. That'll work just the same as what you currently have (yes, it has an expansion tank built in, instead of that small tank in the loft), and then you can - later - remove that LARGE tank if you like, and replace the hot cylinder with an unvented type. (Assuming your cold mains water supply is good enough...)

JGB1955

We replaced our 30 year old 'conventional' boiler with a system boiler a couple of years ago.  We decided to move the boiler up into the loft, providing more cupboard space in the kitchen.  I like the idea of having the immersion heater .... just in case the boiler breaks down but so far, so good! 

330d

Jeepers_Creepers said:

That's the gist of it. But...

A 'regular', 'conventional' boiler means it's 'vented' which means that it needs a SMALL expansion (F&E) tank in the loft. So, do you ALSO have one of these at the moment, or is there ONLY ONE LARGE tank up there (the 'CWS' - cold water storage)? 

Or, does your existing boiler have a pressure gauge? If so, it's a 'system' boiler and not 'conventional' vented.

So, first thing to answer - does your boiler have a pressure gauge, or, does it have a small F&E tank in the loft?

That's one issue. That concerns the actual boiler.

The other - quite separate - issue is the LARGE water tank in the loft, and that it feeds the hot cylinder. That means your DHW (domestic hot water) system is 'vented', or 'gravity'. Ie, the flow from your hot taps ultimately comes from that cold tank in t'loft.

So, that's two different things we are talking about - the type of boiler, and the type of DHW.

CAN YOU CLARIFY - YOU ARE NOT CONSIDERING CHANGING TO A COMBI BOILER? Ie, one that instantly heats your hot water on demand? One that DOESN'T have a hot cylinder?

Ok, assuming you are NOT going 'combi' at any point, when you come to replace your existing boiler, I'd say you definitely DO want to go 'system'. Why? Because it's sealed, and you then lose that SMALL tank in the loft. You'd be nuts to remain 'vented' and keep that small tank.

That's one point. The new 'system' boiler will behave exactly like the existing boiler - it'll still heat up your hot cylinder. If, in the future, you then decide to remove the LARGE cold tank in the loft, then you'll need a NEW hot cylinder, one that is now fed directly from the mains supply - ie it's 'unvented' or 'pressurised'. That won't affect the boiler - the boiler will happily heat up whichever type of hot cylinder you have, vented or unvented (loft tank or mains-fed).

Does that make sense?

Sooooo, do you have a wee tank in the loft for the boiler? Cool. When you replace your boiler, deffo get rid of that and go 'system'. That'll work just the same as what you currently have (yes, it has an expansion tank built in, instead of that small tank in the loft), and then you can - later - remove that LARGE tank if you like, and replace the hot cylinder with an unvented type. (Assuming your cold mains water supply is good enough...)

Wow, great reply. I will try to answer;

1. Current boiler has no pressure gauge.

2. F&E tank? Is this the red tank here - https://i.postimg.cc/PxxQppZs/20201229-155124.jpg

3. No, definitely dont want a combi boiler.

4. Ok understood. I will need a new unvented pressuruzed hot water cylinder

Regarding your last paragraph, I dont understand the conclusion. Can my existing regular boiler be converted to system? Or will I need to buy a new system boiler?

Jeepers_Creepers

330d said:

Wow, great reply. I will try to answer;

1. Current boiler has no pressure gauge.

2. F&E tank? Is this the red tank here - https://i.postimg.cc/PxxQppZs/20201229-155124.jpg

3. No, definitely dont want a combi boiler.

4. Ok understood. I will need a new unvented pressuruzed hot water cylinder

Regarding your last paragraph, I dont understand the conclusion. Can my existing regular boiler be converted to system? Or will I need to buy a new system boiler?

Ah! I remember a previous thread :-)  

Ok, that red thingy is an expansion vessel, and having one of these (flattened) inside a boiler's casing is what essentially turns a conventional boiler into a system type. So, what you almost certainly have there is what WAS a 'conventional' boiler, but it's been turned into a 'system' type.

You DO have a pressure gauge - it's sitting there right above the red thingy.

Ok, that's all good. When you replace the boiler, it'll be with a 'system' type. That means the red thingy can now go, and the boiler itself will have the pressure gauge built in. It'll carry on working exactly like your old boiler, heating up that hot cylinder.

If you then decide you want to lose the CWS in the loft, you'll also have to replace that hot cylinder with an unvented - pressurised - type that's now supplied direct from the mains.

All good.

330d

Jeepers_Creepers said:

330d said:

Wow, great reply. I will try to answer;

1. Current boiler has no pressure gauge.

2. F&E tank? Is this the red tank here - https://i.postimg.cc/PxxQppZs/20201229-155124.jpg

3. No, definitely dont want a combi boiler.

4. Ok understood. I will need a new unvented pressuruzed hot water cylinder

Regarding your last paragraph, I dont understand the conclusion. Can my existing regular boiler be converted to system? Or will I need to buy a new system boiler?

Ah! I remember a previous thread :-)  

Ok, that red thingy is an expansion vessel, and having one of these (flattened) inside a boiler's casing is what essentially turns a conventional boiler into a system type. So, what you almost certainly have there is what WAS a 'conventional' boiler, but it's been turned into a 'system' type.

You DO have a pressure gauge - it's sitting there right above the red thingy.

Ok, that's all good. When you replace the boiler, it'll be with a 'system' type. That means the red thingy can now go, and the boiler itself will have the pressure gauge built in. It'll carry on working exactly like your old boiler, heating up that hot cylinder.

If you then decide you want to lose the CWS in the loft, you'll also have to replace that hot cylinder with an unvented - pressurised - type that's now supplied direct from the mains.

All good.

Perfect. I 'think' I understand now.

So the replacement boiler I am getting now, I will require a system boiler. And the red expansion vessel will no longer be required.

And in the future if I want to remove the CWS, my system boiler will work fine and I just need to replace the hot water tank with a pressureized type.

Is this correct?

Jeepers_Creepers

Yup x 2