1st post here,which type of oil boiler -sysytem or heat only.

[Lofty1]

Hi everyone-im a first time poster and after some info on what type of boiler to fit to my repiped house.
I have an old large house which has currently got a 70kw oil boiler with a single pipe system and pipework is approx 4 inch threaded steel-mega inefficient with school type radiators-the heating system looks to be original to the 1930s house which im guessing was rare in them days-think it used to be worked via a furnace.
The house has been repiped halfway from boiler room in 28mm hep20 plastic and then reduced to 22mm and I'm going to renew all radiators to a modern version of the column type.

I'm thinking of having fitted a Worcester danesmoor 25/32 oil boiler but there are a few different types-which one will i need.

Also I had a heatrea sadia unvented 210 litre tank fitted and repiped separately last year and it came pre plumbed so has a pump and zone valves included in it so at the moment this is just working off the immersion. So will I req a system boiler or heat only.
I've owned the house for 3 years and it is regularly 12 -14 degrees inside so I'm hoping this new system will bring it into the 21st century.
Currently got logburner running every evening to try and stay alive ha ha.
any help much appreciated
I've tallied up all the rads and immersion and I came up with just over 80,000 btu.
So

I

 

[SJB060685]

An accurate heat loss calculation NEEDS to be done first of all. There is a massive difference between a 70kw output boiler and around 25kw load by your calculations.
Once you know the actual heat loss then you can consider boilers.
I would suggest a system boiler but you need to know the actual figures before I can advise you further. There is now a modulating oil boiler on the market but it’s max output is 32kw I believe. If your heat loss is 50kw then that’s not really an option unless you cascade two together with a proper controls system.

 

[Lofty1]

Thanks for the reply.
Re heat loss calcs i haven't got a clue but ive been insulating with celotex and rockwool room by room as the house was actually colder inside than outside previously believe it or not.
I've recently been doing 1 living room insulation for instance and we have taken down the ceiling-put 100mm rockwool between joists still with airflow then overboarded ceiling with 35mm celotex insulated plasterboard over that and in the walls had an new internal 3inch by 2 inch stud wall built internally and put 75mm celotex between studwork and then 62mm insulated plasterboard over that.
That room is nearly 9 foot ceilings and roughly 5 metres x 5 metres in dimension so I've been over insulating in my opinion to get good u value with new double glazed windows also

Fitting x2 column hung from the wall rads approx 14000 btu in that room.

 

[SimonG]

Need heat loss calcs or just urinating in the wind.

Who has fitted the hep?

 

[Lofty1]

A general plumber has fitted the hep20 from boiler room in 28mm roughly half way along the run of the house then reduced to 22m with all rads (16 of them) tails in 15mm and a few drops in 15mm.
General heating engineers from what I've came across dont know much about heatloss/u values/r values
I've had 2 or 3 heating engineers recently look and they've not mentioned anything about heatloss even though it is at the forefront of my mind.
I've had epc certificates done in the past on propertys and I've had spotty teenage kids turn up-first job I'm guessing with not a clue straight from school and on the reports most things are assumed when reports come back
Most of the downstairs have had ceilings down and 100mm rockwool inbetween joists and walls insulated.
House was an energy rating g through the epc when originally bought

I've renewed all the windows-all 31 of them from critall metal single glazed to double glazed units and some to triple glazed depending which way they are facing.
The steps we have done are making big results but central heating is now on the agenda so bigger rads are being added for room sizes and new pipework which should make a massive difference.
The existing heating system is 80 years old i would say (radiators and pipework) and the boiler looks to be 30-40 years-it is a myson floor standing

 

[SJB060685]

If you know the u values of the materials used you can calculate the heat loss off each room. That isn’t going to be quick though but is your best bet at getting an accurate answer.
There is software online that will help you,

 

[exedon2]

You have been given very good advice by Simon G & SJB060685
You either find a heating engineer who really understands heat loss calculations or get them done or do them yourself.
Some of on line free heat loss calculators intended for maybe just on room don't seem that accurate.
We use stelrad stars (version you have to register for) It's free but you probably need a understanding of heat loss calculations to use it.
I personally would not be using the make of oil boiler you mention better options available.

 

[SimonG]

Any heating engineer worth his salt would be doing heat loss calcs and pipe sizing. This service however would come at a price.

I'd be looking at a couple of Hounsfield boilers sized appropriately.

Has the pipework been installed to allow zoning of the installation?

Have you put timbers in the wall at rad locations for hanging/support?

 

[Lofty1]

Thanks for the info re heat loss calcs.
I will try and look them up.
I know the u value of most of the materials but working out the r value seems a bit messier/harder.
Was previously also looking at the grant vortex red boilerhouse model 26/35

 

[SJB060685]

If you add up all the R values you can then find the wall overall u value, then same for roofs etc. it’s a time consuming process but needs to be done.
Honestly I would strongly consider the EOGB Sapphire boiler. Fully modulating with a 6-1 turndown ratio. Full stainless steel hex meaning you can design the system to run at lower temperatures without worry of any back end rot. Opentherm ready and I believe they’re working on making it weather compensation compatible as well.
I love oil burners, all we ever worked on but take it from someone with more than enough knowledge and experience. Most domestic oil boilers on the market are still very primitive. Fixed rate burners, more often than not oversized and only ever run at their sweet spot when at design outside temperature and the boiler output perfectly matches the load. Any day warmer than your design outside temperature and you start getting cycling problems, lesser condensing and overall efficiency, not to mention the constant stop/start cycles at the burner which will decrease burner components lifespan.
Boilers need to modulate and ideally with very good turndown ratios, without that and the system will never be as efficient as it can be.