Search the forum,

Discuss Loft Conversion-Boiler/Unvented in the Plumbing Jobs | The Job-board area at PlumbersForums.net

Status
Not open for further replies.
J

jitno123

HI all,

I am currently in the process of having a loft conversion done, of which I need to upgrade/change the heating and hot water system as the house will be a 5bedroom with 1bathroom and 2 showerooms once complete.

I currently have a Worcester Bosch condensor boiler which is 24kw, which has the usual cold water and header tank in the loft and hot water tank in the airing cupboard. As part of this loft project I'd like to upgrade to an unvented system but I have a few questions about this before I start getting quotes:

1) Direct or indirect? My builder recons direct unvented costs less to heat up water than indirect, I would've thought using electricty would be more on the bills side? He's suggesting doing the water on electric and keep the central heating on gas? (Defo Wont be using builder for plumbing works)

2) Do I need to change my boiler to be able to replace the vented cylinder for an unvented? Or can the system be changed to sealed? I don't mind keeping the small header tank as this can be tucked away in a corner but the large header tank needs to be removed.

3) Looks like my incoming mains is 15mm pipe, so may have to get this upgraded. What happens if I don't? Will the unvented not work at all/poor performance?

4) I have a feeling a 24kw boiler will be too small to heat around 18 radiators (once finished)- Should I change the upgrade at this point too? If so what boiler/setup would you recommend?

Many thanks!
 
i would say indirect would be better (you would require the services of a g3 engy unvented qualified)

depends on size of system as you say later on i would say at a guess need upgrading,
and depends on what your pipework is like

any leaks,
any of the pipework in concrete,
pipework upto an ok standard

best way would be seal the system, i would recommend pressure testing the heating system if you decide to seal the system (give you an idea if there are any leaks)

and yes would suggest a min of 20mm blue alkathene (25mm batter) and a min flow 25 lpm and pressure of 1.5 bar
 
i would say indirect would be better (you would require the services of a g3 engy unvented qualified)

depends on size of system as you say later on i would say at a guess need upgrading,
and depends on what your pipework is like

any leaks,
any of the pipework in concrete,
pipework upto an ok standard

best way would be seal the system, i would recommend pressure testing the heating system if you decide to seal the system (give you an idea if there are any leaks)

and yes would suggest a min of 20mm blue alkathene (25mm batter) and a min flow 25 lpm and pressure of 1.5 bar
As above. I pressed post before finishing my sentence, hazard of posting after a few jars:D:D
 
Definitely unvented and definitely indirect you will still have the option of heating your water via an immersion heater if you require it. Please make sure who ever you get to install the unvented cylinder is G3 qualified.

I forgot to say 25mm (blue pipe) MDPE minimum 1.5 bar pressure and 20 l/min flow rate. If you have more pressure not a problem as the combination valve will limit it to 3.5 bar. A better flow rate 25 l/min plus a bonus.

A Vaillant EcoTEC plus 637boiler is designed for a large home, but it can also be suitable for stone built properties with high ceilings and 13 -16 radiators. It will quite happily heat a large 250-litre water tank.

Good luck with your choice.
 
Last edited:
Hi all, thanks for the reply

Could someone provide me a bit of an insight into the conversion to a 'sealed system' in terms of procedure, cost etc. I had all the rads and thermostats changed a few years back so hopefully that should reduce possible pressure caused leaks. No pipes are in concrete if that makes it better

With regards to the pipe size, would it not run at all on 15mm or does it require a min of 20mm? If required I'd have to get this upgraded(lot of work involving a concrete driveway!).

Thanks a lot
 
With a sealed system you wont have any storage tanks in the roof space. The heating system is filled via a filling loop. An unvented cylinder will not have enough flow through a 15mm pipe. What size pipe do you have below the stop tap?
 
Hi and Welcome to the Forum.

You can change to a sealed system and keep your current Boiler, how old is it?

You need to get a heating Engineer to look this over for you. I agree with a lot of the above, as far as the Cylinder goes and the water main.

You need the house sizing to decide on the Boiler size. I know you say 18 radiators but that doesn't tell us the output of them.
You don't want to under size the Boiler I know but there is no point in over sizing it either, in my opinion.
 
Hi all,

Thanks for the replies and great advice.

The current boiler is a Worcester Bosch Greenstar 24RI installed in 2011, so not too old. A majority of the pipework was changed when the boiler was installed.

Below the stopcock is a 15mm pipe I believe running from the street. How can I get around this? Upgrading the pipe isn't an ideal option for me as it would involve breaking my driveway, however if needed I could possibly have this done. Is there another option to accommodate for this, ive read that an accumulator may be able to help?

I've just ordered a water pressure gauge to check the mains pressure...how can I check the flow rate?

Thanks
 
The only way to get around using a 15mm pipe on the incoming main is to use an accumilator or a break tank and pump set, both are large in size and fairly expensive, the accumilator will need to be sized in conjunction with the size of your unvented cylinder and your standing pressure and working flow rate.

The break tank and pump set will be the most expensive option and will need maintanance and of course if it stops working it will limit the hot water supply.
 
Status
Not open for further replies.

Reply to Loft Conversion-Boiler/Unvented in the Plumbing Jobs | The Job-board area at PlumbersForums.net

Creating content since 2001. Untold Media.

OFFICIAL SPONSORS

OFFICIAL SPONSORS

Back
Top
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website. For the best site experience please disable your AdBlocker.

I've Disabled AdBlock