Condensing boilers, Kidd, heatstore and unvented

[catlane]

We have a large farmhouse with a decrepit oil boiler and need a modern heating system. We are on heating oil, but would like to use solar hot water heating and ideally the solid fuel Rayburn in the Kitchen.
Our power requirements have been estimated at 200000 BTU by two engineers (all rads together)

Fou rquestions really

We have been recommended a condensing boiler, but are these reliable with oil. Do they fail prematurely due to suplhites and corrosion?

The Archie Kidd boiler..is it a better option?

My wife really wants a mains pressure hot water system, so assuming are flow rate is enough (which it may not be, as one engineer has assessed it at 19 lpm, but that may not be accurate) how do heatbank / thermal stores compare to an unvented type cylinder?

Can the rayburn only be plumbed in to a traditional gravity fed system

Cheers

David

ps How do you work out your flow rate into the house

pps Apologise for any terminology cockups as this is not my field, just the owner of a chaotic house

 

[Agile]

I am amazed by the size of your heating requirement. That would cost about £4 per hour to heat.

Yours is 60 kW while the average semi is only about 11 kW.

It also implies about 30-40 radiators !!!

Do you really need to heat the whole place??? Could you improve the insulation?

It seems you already have some professional advice and the questions you are asking could be answered in a good size book!

Tony

 

[Gary59]

As far as I can see you really need much more information than I could answer or even like to guess sitting here.

My suggestion is use British Gas (Free Information service).!

Make an appointment with them, let them spend 3 hours working it all out and quoting on the job, they will then leave you a lovely folder full of bumph for your perusal.

The advantage of this is that you can probably get the same job done for 75% of the price...!

 

[catlane]

We have got quite a lot of radiators, but one annexe which has a separate boiler is off unless we have guests, and clumps of the house are unheated at any one time. Whatever system we have, zoning seems to be mandatory. Insulation, leaky windows and the like is something else to address. It's all a disaster area.

I think the problem with british gas is that we are very rural, awith no mains gas. I am afraid its domestic heating oil, or LPG and a septic tank for us.

Ta

Davdi

 

[Gary59]

David as I thought your tasks ahead are far more reaching than simple btu calculations and well beyond the realm of this forum.

I wish you every success with your renovation.

 

[catlane]

Your right, the questions are not simple, and I am asking way too much. I am going dizzy looking at the options, but want some way of taking the heating engineers on on equal terms. Of course I can't do this, but the more I understand the options, the better the chance of me getting the right system at an acceptable cost.

Thanks

D

 

[Nigelo]

Catlane

I have recently changed to a condensing oil boiler by Grant (their Vortex model) and swear by it. The heat exchanger is stainless steel and has a 5 year manufacturers guarantee out of the box - Only condition is annual service and the usual inhibitor in the system. If they were that fragile, the guarantee would be substantially less but then Grant is one of the better ones if not the best. They manufacture Kitchen, Utility and Outdoor Vortex modules in various outputs and are definitely worth looking at.

IMO, there is a lot of crap spouted against condensers, largely out of ignorance. My Grant had a flue gas temperature of just 38degC and shows why they are so efficient (98% in my case).

Archie Kidd's boilers are not an alternative but in fact the same though with a cast iron primary heat exchanger and a second unit above the first. He pioneered condensing oil boilers back in the '80s and they are built like the proverbial brick lavatory.

I'm no heating engineer but if you have seasonal demand in different parts of your farmhouse, why not consider splitting the load between 2 smaller boilers so that at least 1 could run efficiently most of the time.

Solar heating is something I am looking at (Sonnenkraft) but is better suited for DHW requirements. That said, a Polish Architect friend of mine designs eco-friendly housing with integrated solar heating and that provides 25% of all heating / DHW in Polish mid-winter (-20degC) rising to 100% between April and mid October. However, he uses heating coils embedded in breathable walls which is obviously not suited to retrofitting.

Finally and IIRC, you are not allowed to use solid fuel with unvented systems as you cannot effectively control overheating.

Hope this helps

 

[doitall]

With multiple fuels the store would be the best bet provided the mains is up to the task, although you can overcome this anyway with a break tank and pump set in an outbuilding.

Aga I'm not sure if the need to be open vent.

Another option if you hve the ground to go with the farm house is Ground or air source heating.

www.3rdrockenergy.com

Send me an email if you want a few pics of the setup

MOD 2

i do hope that wasn't advertising

 

[catlane]

Two boilers is an idea. The only quote we have had so far is for two Grant Vortex 26/36 external boilers, which would be in what I suppose is a master/slave arrangement, with the roles being reversed yearly. The cost of the boilers alone is £3000 before everything else is considered. I suppose the areas we would like to zone off are an annexe and the converted roof space, but I can't see another way of providing for these separately, as my wife will not have internal oil boilers due to the smell.

I really like the idea of plumbing in the Rayburn, and I had previously heard that these could not be used with an unvented system, so that may be a reason to avoid unvented, along with possibly inadequate mains flow. Installing a reservoir to get round the flow issue seems costly. Geothermal is interesting as I hadn't considered it.

Thanks for the feedback

David

 

[Nigelo]

Unless I have misunderstood, you may have a solution after all - persuade your wife. The Vortex boilers (and I guess all modern oilers made for internal use) do not smell at all, not even a trace. It it does, then it has not been installed correctly.

My Vortex Utility model is installed in a utility room and even the slightest smell would be instantly detected even with the required ventiliation. Try and see one in action or speak to Grant's Customer service.

Hope this helps

edited to add that they also extremely quiet

 

[doitall]

Nothing to stop you having a twin or even three coil cylinder, then the heating can be sealed and the aga could be open vented.