New cast iron boilers

TPM

Just wondering what your opinions are on new cast iron boilers?


I was looking at one for a place where a condensing boiler wasnt suitable.

While looking through the tech spec I noticed that for the 27kw model the efficiency is claimed to be 89.9% 100% load 70oC and 90% at 30% load 50 oC.
I couldnt find any information that I could compare the Cast Iron boilers to the similar Grant Vortex which has a SAP rating around 93%.

The efficiency difference between then is quite low taking into account the price difference and the fact that it is a more straight forward non condensing boiler.

Does anyone know how these efficiencies compare in reality

JohnnieK

Saint Roche do a cast iron boiler that is quite efficient 88% I think and it can be run at low temps too.

TPM

Yea its the Saint Roche I was looking at they seem a fairly decent boiler. That's great efficiency from a non condensing. boiler.
Have you fitted any johnnie?

shane0007

TPM wrote: »

Just wondering what your opinions are on new cast iron boilers?

CI boilers can be excellent well built boilers that can last a lifetime if they are of good quality. The down sides are if they are not serviced properly and very thoroughly, they quickly suffer from metal fatigue and higher flue temperatures will become very apparent.

They take much longer to heat up but equally they hold onto their heat for longer so it is always best to have the pump on a stat to dissipate heat from the boiler. Harder to do with a fully zoned system.

Be careful of lower return temperatures as it can cause thermal shock and crack the cast iron. Of course if MI's allow then a mixer may not be required.

TPM

shane0007 wrote: »

CI boilers can be excellent well built boilers that can last a lifetime if they are of good quality.

There are alot of old cast iron boilers around over 30 years old specially in churches and community halls with plenty of life left in them

Do you know how comparable the efficiency figures of the saint roche are in relation to the quoted ones for the condensing boilers, the saint roche ones seem to be very high?

shane0007

The only thing I would be weary of, to be at an efficiency of boiler 88% you are in the realms of flue temperatures of 125C. Once below 125C, the boiler could potentially begin to condense which as we all know will absolutely destroy a steel or CI heat exchanger. It would most certainly require a mixing valve between the flow & return to ensure higher return temperature.

JohnnieK

TPM wrote: »

Yea its the Saint Roche I was looking at they seem a fairly decent boiler. That's great efficiency from a non condensing. boiler.
Have you fitted any johnnie?

No not yet but I'm dying to.

TPM

shane0007 wrote: »

The only thing I would be weary of, to be at an efficiency of boiler 88% you are in the realms of flue temperatures of 125C. Once below 125C, the boiler could potentially begin to condense which as we all know will absolutely destroy a steel or CI heat exchanger. It would most certainly require a mixing valve between the flow & return to ensure higher return temperature.

Thanks.
True condensation doesnt go well with ferrous heat exchangers.

There are a few farmers need new boilers but are refusing to change away from gas oil and approved gas oil settings for condensing boilers are not to readily available so the CI boilers may be an option.

TPM

JohnnieK wrote: »

No not yet but I'm dying to.

Me to to be honest, IMO they seem to be a good option in certain circumstances even over some of the condensing boilers out there, specially when you are under 5oC efficiency difference

shane0007

TPM wrote: »

There are a few farmers need new boilers but are refusing to change away from gas oil and approved gas oil settings for condensing boilers are not to readily available so the CI boilers may be an option.

If they are a bit flush, they could consider the Viessmann Vitoladen oil boiler. It is fully modulating on oil and it will only run on Gas Oil.

Downside = Cost of boiler €4,500!!!

JohnnieK

To the best of my knowledge the Saint Roche is coated with something in the event of condensation and protects the heat exchanger (so I've been told).

TPM

shane0007 wrote: »

If they are a bit flush, they could consider the Viessmann Vitoladen oil boiler. It is fully modulating on oil and it will only run on Gas Oil.

Downside = Cost of boiler €4,500!!!

I did say farmers

Modulating oil would be nice, I reckon it will be a long time before we see affordable options though.

TPM

JohnnieK wrote: »

To the best of my knowledge the Saint Roche is coated with something in the event of condensation and protects the heat exchanger (so I've been told).

Sounds great, but I have my doubts about a coating lasting the lifetime of th boiler

shane0007

TPM wrote: »

I reckon it will be a long time before we see affordable options though.

Riello have one at test stage right now. Should be ready for market in a year or two. It will be a retrofit for condensing boilers.
It modulates to 50% so a 26kw can fully modulate between 13kw & 26kw and anything in between so it is not two stage.
It will require specialist certification to work on it as it will have an operating pump pressure of 30bar so you don't want the homeowner or a clown at it if they do not want to lose a finger or two!
Cost wise, somewhere in the realms of €500.

Talk to Stephen at Precision, he'll give you the heads up, from what I remember the heat exchangers are the same/similar to vissmanns. I fitted two boilers and as a gasman I think there gggreat.

TPM

shane0007 wrote: »

Riello have one at test stage right now. Should be ready for market in a year or two. It will be a retrofit for condensing boilers.
It modulates to 50% so a 26kw can fully modulate between 13kw & 26kw and anything in between so it is not two stage.
It will require specialist certification to work on it as it will have an operating pump pressure of 30bar so you don't want the homeowner or a clown at it if they do not want to lose a finger or two!
Cost wise, somewhere in the realms of €500.

Sounds promising alright and price wouldnt be too bad in that range.

30 bar is fair pressure, it must be some pump specially when the oil pump has been the main issue with Riello burners.
Plenty of scope to get the set up wrong too I bet.
What way will the certification work, will it be by Riello, or through general hydraulic certification?

shane0007

Nobody knows how the certification will work at this stage. The existing Riello pump can quite easily get extremely high pressures. I had a call out to a new install that was sooting. Pressure gauge went off the scale of the gauge. The issue? Installer inserted the bypass screw for a one pipe configuration!
Also it will be easier to obtain a higher pressure using Class D as it is a 35 second oil rather than C2 being a 28 second oil. The modulation will also be done through the pump from what I am told.