New Boiler (Heat only) for use with a Thermal Store (Kingspan Flowmax)

[Agile]

Most thermal stores likes 82 C as that was what all non condensing boilers would easily give.

Current condensing boiler are designed for a flow temperature of 75 C although most will give more although some are only more when the heat output is lower than their max.

I recommend you choose a boiler whose spec includes a max heating flow temp of at least 80 C.

But a flow of 80 C is not so ideal for rads using current design parameters.

Being able to control with a higher flow on HW and lower on CH would be better.

You need an installer who has experience of controlling thermal stores. Most are more experienced at taking them out and fitting a combi.

With a boiler operating in non condensing mode don't expect much increase in efficiency over your current boiler. I am not yet convinced that there is any logic in what you are trying to do.

Tony

 

[Razor900]

Disclaimer first I work for Intergas as most of the regulars know!

Couple of points;

@Dan Robinson, Tony is right, some systems use a three port valve and heat the rads directly from the boiler with the store just being used for hot water production and some use multiple pumps and have everything running off the store. You can get multiple flow temps from our boilers.

Our maximum flow temp is 90 degrees.

You can run the boiler with or without pump overrun, it doesn't need to be changed in the software though.

It does need a permanent live as well as a switch live.

It's about the closest thing you'll get to a cast iron type boiler today.

No boiler will condense properly at that temp. I would advise you to very carefully check and see how much life the thermal store has left in it (usually around 10/12 years) and perhaps consider a complete change to either an unvented cylinder or a combi depending what your hot water requirements are.

Of course you could always use one of our combi's as a heat only boiler for now with the store and convert the system to a combi when the store fails!

 

[catflap2]

Of course you could always use one of our combi's as a heat only boiler for now with the store and convert the system to a combi when the store fails!

Is there any downside to this?

The store was replaced by BG under their servicecare contract about 5 years ago as the original one failed after 17/18 years so I was hoping that this one would have 10+ years life left in it.

With this store the boiler heats the Store and a separate pump will circulate the store water through the rads so they are not heated directly from the boiler.

I guess the alternative now as you say would be to rip it all out and stick a Combi in. Would that be a good idea? I assume we wouldn't be talking about a huge amount more if we do this now ( i.e. hundreds not thousands extra) The couple of engineers we've had so far didn't really offer that just a like for like swap so I hadn't really considered it as I do like our mains pressure water.

I will get a quote from a local Intergas installer as well not sure there is one in Bicester or not but there are a few down the road in Oxford.

 

[Razor900]

If you only have one bathroom a combi would probably be ok. However it will never give water as quickly as a thermalstore although it will never run out. The other downside of your store is having the rads very hot although on the plus side they heat up really quickly! All pro's and con's

As the store is only 5 years old personally I would forget the combi and go for another heat only boiler which gives you the option to fit an unvented at some point in the future if the store fails.

I can recommend @muggles very highly although I'm not sure if he goes as far as you, he definitely covers Banbury or I am in Northampton.

 

[HootingOwl]

Look on Ebay for someone selling an Ideal Classic cast iron boiler. Against building regs but far more environmentally responsible than fitting a modern shytebox that will not be efficient on a thermal store.
If you must have a new boier then get the pump overrun wired up no matter what the instructions say about it not being necessary. Then get a Viessmann 100 compact heat only 19kW. Glow worm and Vaillant have had the value engineers in and some of their latest offerings are not worthy of the brand.

As for Worcester, you can buy better for a lot less. Who do you think is paying for all those adverts?

Intergas a niche choice but generally they are fitted by installers who know what they are doing. Cowboys do not fit Intergas - they fit Worcestersand hide behind the brand.

 

[catflap2]

I definitely need to get a visit and quote from an Intergas engineer so I must get on and sort that.

However had a visit from a very nice and knowledgable engineer this evening. Basically ran through a number of different system replacement options (combi etc.) from Atag, Veissmann etc but when he looked at the store he said it looks pretty new and well insulated and all the pumps and bits all look new ( which they are ish) so he would probably just replace the boiler with a like for like swap.
At this point he went completely away from all the makes we had been talking about and said straight away for a store like this use the Baxi as it doesn't need a pump overrun (pretty much as per the advice at the beginning of this thread). What he then said seems to make a lot of sense to me. Basically if you have a boiler using a pump overrun then with this set up you are just pumping very hot water from the store through it which is pretty close to 80c so the pump will just run for ages as its not cooling the boiler like a normal tank would full of water 20 deg or more cooler. He said the Baxi is great for use in these instances and that is pretty much what they recommend fitting with a store regardless of what wiring is in place. He said technically the Viessmann can be run without overrun but it doesn't really like it and the Baxi is much better in these instances. Convinced me anyway and was very helpful though I really would like to see what Intergas offers so I have a choice.

Anyway thank you to everyone so far for all the advice, I'm slowly learning a lot more about my heating system.

 

[muggles]

If you only have one bathroom a combi would probably be ok. However it will never give water as quickly as a thermalstore although it will never run out. The other downside of your store is having the rads very hot although on the plus side they heat up really quickly! All pro's and con's

As the store is only 5 years old personally I would forget the combi and go for another heat only boiler which gives you the option to fit an unvented at some point in the future if the store fails.

I can recommend @muggles very highly although I'm not sure if he goes as far as you, he definitely covers Banbury or I am in Northampton.

Thanks for the recommendation Razor! Just hope the OP doesn't mind waiting a while, I'm booked up until November... he's made contact though so we'll see how it goes

 

[RTFB]

There is much to be said for fitting a four pipe system boiler with weather compensation. You would disconnect the radiators from the thermal store, and connect them to the radiator output on the new boiler. The boiler will then condense most or all of the time in central heating mode, which it can't do when everything comes via the thermal store. The thermal store just supplies domestic hot water. This could reduce gas consumption by up to 15%.

 

[hertsboilers]

There is much to be said for fitting a four pipe system boiler with weather compensation. You would disconnect the radiators from the thermal store, and connect them to the radiator output on the new boiler. The boiler will then condense most or all of the time in central heating mode, which it can't do when everything comes via the thermal store. The thermal store just supplies domestic hot water. This could reduce gas consumption by up to 15%.

Up to 15%?

It is too much to be true!

 

[Dan Robinson]

Intergas is a timed pump overrun. Not temperature.

 

[Agile]

Whatever boiler is chosen it is worthwhile changing the system slightly so that the store is only used for the hot water and the boiler drives the rads separately.

That enables the ( right ) boiler to operate at a lower temperature so that it is most efficient as a condensing boiler is designed to do. At least Ray understands how these stores can be used!

Typically a boiler is only used for 15% of the time to produce hot water during the year. So that saving becomes significant.

Tony

 

[Dan Robinson]

Where the feck do you get your numbers from Tony? I swear you use a random number generator for your barking prices and invented statistics.

 

[Steelmasons]

Agile constantly makes these ridiculous sweeping statements , when challenged he crawls back into his shell..
..and so it goes on..
15% FFS..

 

[Agile]

Rather that broadly disagree with my figures, why not be more helpful and quote your own ( if you have any )?

 

[hertsboilers]