Worcester 36cdi - How many radiators max?

[boilernoob]

Hi everyone,

I currently have a 5-year old Vaillant 835 ecotech plus used to power 12 radiators in the house. I'm being recommended a Worcester Bosch 36cdi to replace it, but I'm anxious and confused because the Vaillant has a 30kw CH output, but the Worcester has only 24kw CH output.

Is 24kw enough for 12 or more radiators?

 

[muggles]

Yes, it's loads. Most radiators are under 1kW each. Much more important than the max output is the min output, as a lower minimum will be more efficient. Your existing Vaillant can go down to 5.8kW, whereas the proposed Worcester can only go down to 7.15kW, so it'll be less efficient & more expensive to run.

Why are you replacing a 5 year old boiler? All the spares are still available

 

[boilernoob]

Thanks very much muggles. That's really helps me a lot.

Honest answer is that my grandad lives with me and has been offered a boiler grant. So the choice is to either stick with the existing 5-year old boiler or replace it with a new one within the grant.

Also please accept my apologies, but I forgot to add that I was also recommended:

• Vailliant Sustain
• Baxi Assure

So if you think any of these are better, then do let me know.

Thanks.

 

[muggles]

Keep the existing one. You don't need a new one, it won't be any cheaper to run, and grant-funded boiler installations are often launched on the wall with the minimum of care. The grant funding isn't a bottomless pit, don't take it away from someone who might actually need a new boiler.

 

[boilernoob]

Keep the existing one. You don't need a new one, it won't be any cheaper to run, and grant-funded boiler installations are often launched on the wall with the minimum of care. The grant funding isn't a bottomless pit, don't take it away from someone who might actually need a new boiler.

Thanks. I appreciate what you're saying, but my grandad is over 100 years old and the reason to replace it was because the Vaillant is now 5 years old and although it's not very old, we've already had to replace some of it's parts and I think it's almost out of warranty.

Could you at least help me with one issue that the Vaillant is currently having? All radiators work fine, except one in the attic, which is only slightly warm. When I adjust the thermostats downstairs to lower numbers (2 or 3), then the attic radiator heats up much better. But then this means the rooms downstairs are much colder.

Why does this happen and what's the solution to this problem?

 

[muggles]

The system needs balancing using the valves

 

[boilernoob]

The system needs balancing using the valves

By valves, you mean as opposed to Thermostatic valves? If so, they've already been done, although not sure how the plumber measured the balancing.

 

[Gasguru]

No the lockshield valves...on the other end of the rads.
5 year old boiler and the tax payer is funding a replacement...no wonder we're bankcrupt

 

[boilernoob]

No the lockshield valves...on the other end of the rads.
5 year old boiler and the tax payer is funding a replacement...no wonder we're bankcrupt

I appreciate what you are saying, but please don't punish me for being honest about my grandad's circumstances as I don't make the rules of who gets what. I could have easily made up a fake situation, but I didn't, therefore I would be grateful if we could simply stick with the DIY topic.

Regarding the lockshield valves... That's what I also meant... These have been fine tuned, but I'm not sure how or if they are correct.

 

[muggles]

If you're getting some rooms getting warm and others not, it sounds like it wasn't done correctly

 

[boilernoob]

If you're getting some rooms getting warm and others not, it sounds like it wasn't done correctly

Thanks muggles. I'm just wondering whether I could do the balancing myself and if si how or where do I start from?

 

[muggles]

There's an FAQ on balancing at the top of the forum.