Opinions on boiler upgrade plans?

[dannyboy85]

Just looking for some options here.

Third floor apartment, currently have an outdated Potterton Powermax HE 85L boiler (Essentially an unvented 85L tank with a 'system' boiler all in one box - I think?) Installed 2006.

BG (Yes I know) have advised it is obsolete / limited parts available, & I've been thinking of upgrading for a while, to preempt the inevitable & future proof myself.

Considered a combi, but think the gas pipe may be an issue. To my knowledge it's all in 22mm, with at least ten 90 degree bends... Can't see much of it as it's in the wall / floor, but it comes up from ground level into my kitchen floor & then an unknown route to boiler (about 6m away).


Not a huge fan of Combis anyway, & am used to the good pressure hot water from unvented system, so would I be best with a small unvented tank & system boiler? (Should have space for this in airing cupboard where existing boiler sits).

I have 4 room rads, 2 towel rails, 2 showers and 1 bath.

Any thoughts on what would be best?

Ta!

 

[Jurassicspark]

By the looks of it, the gas pipe would be fine but the GSR who will install your boiler will measure the pressure to ensure if your supply will be able to accommodate a combi boiler.

A combi boiler will deliver a certain amount of litres of hot water at a given temperature. For example, 10 litres per minute at 50C. If more than one outlet is open eg, shower and one tap that 10 litres would be shared between the two outlets disproportionately depends on the pipework layout etc. If only one person is having a shower just a regular combi would be fine but if the family is large and multiple showers are being used at once then it would be wise to add a hot water cylinder.

If there isn't anything wrong with your boiler right now I would recommend sticking with the existing setup.

 

[dannyboy85]

By the looks of it, the gas pipe would be fine but the GSR who will install your boiler will measure the pressure to ensure if your supply will be able to accommodate a combi boiler.

A combi boiler will deliver a certain amount of litres of hot water at a given temperature. For example, 10 litres per minute at 50C. If more than one outlet is open eg, shower and one tap that 10 litres would be shared between the two outlets disproportionately depends on the pipework layout etc. If only one person is having a shower just a regular combi would be fine but if the family is large and multiple showers are being used at once then it would be wise to add a hot water cylinder.

If there isn't anything wrong with your boiler right now I would recommend sticking with the existing setup.

Thank you for replying.

The BG guy said gas pipe would likely not be sufficient for a decently enough combi to give me the hot water flow I currently have. As it is a long run up 3 flights then all the joints etc.

I am the only person living here, so two outlets at once would be impossible most of the time.

Existing boiler is in perfect working order, except:

- Almost 20 years old
- Noisy at times
- Limited parts available
- Tank slightly too small to fully fill bath hot enough
- Could pack in at any moment!
- Badly regarded by plumbers. Hard to find people still willing to work on it.

Due to this, I have to keep the BG boilercare running, and that gets more expensive every year due to boiler age.

So I'm thinking I could spend that monthly amount on a new system with 0% credit and 10 year guarantee.

But then I don't want some underpowered combi where the HW is just a trickle, that's why I was looking at another unvented system.

 

[dannyboy85]

Also does anyone know if a Morden day boiler would be much more economical / running costs wise than a 20 year old Potterton?!

 

[Jurassicspark]

Also does anyone know if a Morden day boiler would be much more economical / running costs wise than a 20 year old Potterton?!

Mhmm, I don't know if your a boiler is condensing but if it is, then upgrading won't really lower bills much.

 

[dannyboy85]

Mhmm, I don't know if your a boiler is condensing but if it is, then upgrading won't really lower bills much.

Yes, it looks like it is.

Summary. The Potterton Powermax HE 85 CP has a SAP seasonal efficiency rating of 89.5%. The Powermax HE 85 CP is a Condensing Combi boiler with a maximum power output of 24.0kw that uses Gas as its fuel source. This boiler will provide efficient heating and subsequently reduce fuel bills and carbon dioxide emissions.

So I guess it's already pretty efficient.

Interesting to see that it's described as a 'Combi' boiler, and 24.0kw.... Being as it heats a tank, why would it be a combi? And does that mean my gas pipe is at least ok enough to power a 24kw combi?

 

[Harry Bloomfield]

- Tank slightly too small to fully fill bath hot enough

Any possibility, to increase the temperature of stored hot water? That would allow you to add more cold, thus stretch the hot water some.

Interesting to see that it's described as a 'Combi' boiler, and 24.0kw.... Being as it heats a tank, why would it be a combi? And does that mean my gas pipe is at least ok enough to power a 24kw combi?

A combi, normally has to have a higher Kw, enough to instantly heat up the water. A system which heats stored water, can be much lower Kw, just enough to heat your home.

 

[dannyboy85]

Any possibility, to increase the temperature of stored hot water? That would allow you to add more cold, thus stretch the hot water some.



A combi, normally has to have a higher Kw, enough to instantly heat up the water. A system which heats stored water, can be much lower Kw, just enough to heat your home.

Yes, there is. I notched it up a bit today actually, it doesn't give degrees on it, just a + and -, it's about 3/4 of the way, and tap water is scalding hot, but still couldn't really get tonight's bath as hot as I'd like.

And for your second comment, that's why I was surprised my Potterton would be described as a combi, and would be 24kw.

Being a hot water tank, I'd expect it to be less.

Thank you for replying.

 

[muggles]

BG are often quick to suggest parts are becoming obsolete, but in your case it looks like they actually are. The Powermax isn't a great boiler anyway though. It's officially a storage combi, although it has the same effect as a system boiler with a small cylinder attached. And yes, you could achieve the same performance with a 24kW system boiler and a small unvented cylinder.

 

[Murdochcat]

If the boiler is working wait until after Easter then find a local GSR by asking friends and neighbours

BG have a reputation for overpriced installs

 

[JohnD]

- Tank slightly too small to fully fill bath hot enough

Opinions vary, but you need about 100 litres. Current practice is to fit larger unvented cylinders.

One thing you could do, is part fill the bath, and wait till the boiler gets some more ready. Spend your time shaving and brushing your teeth or cleaning the WC

If you add some bath foam the layer of bubbles will insulate the top of the hot water, as well as reducing steam in the bathroom.

A modern 24kW boiler can heat about 8 litres per minute (less in winter as the incoming water is colder) if it is not heating the radiators at the same time). Combis are notoriously poor at filling a bath with really hot water.

Even if your system is less efficient, ten minutes will be a help.

Scale or sludge will reduce efficiency

 

[dannyboy85]

BG are often quick to suggest parts are becoming obsolete, but in your case it looks like they actually are. The Powermax isn't a great boiler anyway though. It's officially a storage combi, although it has the same effect as a system boiler with a small cylinder attached. And yes, you could achieve the same performance with a 24kW system boiler and a small unvented cylinder.

Thanks for your input, yes I know it's not regarded as a very good boiler, even though it's served for 20 years and still going strong.

24kw seems high for a system boiler, I think? Surely I wouldn't need that.

 

[dannyboy85]

If the boiler is working wait until after Easter then find a local GSR by asking friends and neighbours

BG have a reputation for overpriced installs

Yes I agree about waiting until later in the year (It'd be madness to do it in the winter & leave myself with no heating!)

I know BG are going to be costly. It'll be a complicated job with scaffolding required, etc. So I'm not sure local GSRs would be willing to take it on!

I suppose a quote from BG would at least give me an idea of what would / wouldn't work, and a rough (but inflated) idea of cost!

 

[dannyboy85]

Opinions vary, but you need about 100 litres. Current practice is to fit larger unvented cylinders.

One thing you could do, is part fill the bath, and wait till the boiler gets some more ready. Spend your time shaving and brushing your teeth or cleaning the WC

If you add some bath foam the layer of bubbles will insulate the top of the hot water, as well as reducing steam in the bathroom.

A modern 24kW boiler can heat about 8 litres per minute (less in winter as the incoming water is colder) if it is not heating the radiators at the same time). Combis are notoriously poor at filling a bath with really hot water.

Even if your system is less efficient, ten minutes will be a help.

Scale or sludge will reduce efficiency

Thanks for replying.

Yes I was thinking about 100L would probably be about right.

I must admit, with the Potterton, the hot water tank does recover very quickly, usually after 10 mins I have HW again.

But that's a bit of a faff so I generally just use the kettle to top up the bath.

Either way though my main concern is the age & reliability of the Potterton, and difficulty finding engineerings willing to work on it!

 

[muggles]

Thanks for your input, yes I know it's not regarded as a very good boiler, even though it's served for 20 years and still going strong.

24kw seems high for a system boiler, I think? Surely I wouldn't need that.

Yes and no. If you want fast recovery on an unvented cylinder you need the power to be able to achieve that. Get a boiler with good modulation, set for hot water priority, with good quality load- or weather-compensating controls. This will give you the day recovery you're looking for, and very efficient heating. If you ask BG to do this though you'll just get a blank stare, they don't have the technical knowledge to be able to achieve such a setup.

EDIT Which bit of Warwickshire? I'm in West Northants....l