House ventilation

You could always fit a temporary cover and remove when the service is due - by foam, I assume it's only reducing the air flow and not stopping it ? Is there any way of sheilding the outside vent a bit from the wind ?

Is the boilerman suggesting that it requires an unobstructed airbrick on the other side of the house to function safely? My boiler has its own dedicated air inlet. Seems to be exceeding his brief a bit there.

Normally houses of that vintage are very air-leaky anyhow. When you blocked the airbricks, did you get any damp/mould issues? And did the boiler work properly?

My approach would probably be to change my heating engineer...

What the gas fitter is on about is having a fresh air supply to the boiler, as it takes it from inside the house. Ideally, therefore, the air vent should be at or near the boiler. If it has an outside wall, put a vent there, and you can then block off the other (large) one. If no outside wall, you can duct air from outside under a suspended floor to the boiler cupboard.

The boiler inlet is inside the house, never had any damp issues when the vent is blocked. I did suggest a cowl on the outside to stop wind blowing through to the engineer and he said that wasn't allowed and he'd have to remove that too. He didn't have any suggestions about what I could do to help, not very helpful.

As said above the boiler needs a supply of fresh air otherwise you risk carbon monoxide poisoning. I would be looking hard for a way of ducting a supply of fresh air from outside to the boiler cupboard, under the floor or through a horizontal duct below the ceiling perhaps. You would have to ensure sufficient air supply.
I am not a heating engineer 🤐

Why would a boiler need fresh air Vs normal stagnant air? Surely any carbon monoxide goes out the flu.

I'm interested as my boiler is in a cupboard that's in the middle of my house with no access to fresh air.

How old is your boiler and what does the flue look like? I'm guessing you may not have a balanced flue if the HE is being so firm about it. Even so, it should be possible to achieve the necessary air intake a bit closer to the boiler rather than dragging cold air in from a vent half a house away.

Do you have any 'open' gas appliances he's servicing at the same time? Gas fires, hobs/ovens etc.

The boiler is 6 or 7 years old, The flue is just steel pipe about 15-20cm in diameter the inlet is separate and is 30cm diameter flexible foil ducting that vents to the hall, there are no other gas appliances, there's no nearer outside wall, the house is designed around the warm air heating with a central column which contains the boiler and the other rooms are built around it, so the vent is always going to have to drag the air half way across the house, the location of the exterior vent is actually the nearest point to the boiler inlet. It sounds like I'd need to I'd need to think about a fixed inlet to an outside wall through the floor space, but if it needs to be the same size as the inlet at the boiler it would have to be huge (30cm dia) not sure where that would even fit.

Yea, I'm not convinced it's a CO risk either, our house is similar, there used to be an air brick in the kitchen (now sealed up), but nothing near the boiler. the boiler cupboard used to have vents in the door so it could draw air from the rest of the house, but there's no dedicated inlet to the house itself.

Been like that since before we moved in, and before us it was a rental, so it's had regular safety checks.

Ah, I get you, and now understand where your heating dude is coming from. The boiler inlet needs to get its air from somewhere.

Surface area of the inlet ducting is just over 300cm squared, and your airbrick is 400cm squared, so it's about right, although the engineer could give you an idea of what's possible.

Have you stuck your head into the subfloor to see what, if any, ventilation that already has? Mine has a few airbricks feeding into it.

AFAIK, if it's a balanced flue boiler it doesn't need ventilation as its air supply and exhaust is via the flue. It sounds like the OP's boiler is "open flued", so a separate air supply is needed.

It will be because it's an open flue boiler. If the house is too airtight the nasty stuff including the silent killer (carbon monoxide) may not exit via the flue to the roof. Those of us with wood stoves and a fairly air tight house will be familiar with cracking open a window to help get the fire lit and encourage the smoke to go up the chimney...it's the same idea!

We used to have an 30yr old open flue boiler (wet not blown air), you could see the flame when it was running, that's definitely open flue.

I fitted a new plastic grill to the inside of our air brick and the gas engineer said we had to remove it as he knew the ventilation area was below the requirement (it was lots of squares rather than louvres). So they are fussy and definitely don't like vents that can be closed!

PS Hopefully you have a monoxide detector.

Maybe you could create a new high level vent and pipe it across the ceiling to the central cupboard, either box it in or use neat round or square trunking. You'd need to ensure it was acceptable first as 3 metres of pipe may affect the cm² area required and the last thing you'd want is the wind to risk reversing the flue direction!

I think I would trust the gas engineer rather than the internet on this issue. He has spent thousands on training and insurance and risks criminal prosecution if his actions are incorrect.
By all means get a second opinion from a gas engineer as like all jobs there are good and bad ones.
If it is opened flued then air for combustion is critical, servicing and maintenance too. Do not rely on CO alarms they are a second line of defence and no substitute for maintenance.
My advice would be to try to find an alternative way of providing combustion air but that can be complicated if it is ducted or taken through multiple rooms.
Or get rid of it and fit a balanced flue boiler and radiators

Ha, I won't be getting rid of it, it's cheap to run, and I really like the flexibility you get with furniture when you don't have to worry about where the radiators are, the only slight issue is that upstairs is a couple of degrees cooler than downstairs when it's cold and windy. I was just thinking that with air getting sucked out of the house, I could save some more money by stopping that, sounds like the proper solution isn't likely to be worth the bother though, maybe just cover the vents on those cold windy days when it is an issue. We have a CO sensor and the boiler is serviced every year, and there's very little to actually go wrong with it anyway as it's amazingly simple.

Is it feasible to add a warm air duct to the upstairs?

I had this issue on my last place in the UK, massive airbrick in the living room, probably 200mmx200mm, facing the prevailing wind. Funnily enough a 70's build 2 bed with warm air heating!
The worst thing was that the wind actually forced the air in, rather than it being drawn in by the boiler/flue arrangement. So all along that wall (where the sofa was) you had a cold breeze whenever the wind got up and the curtain that covered the edge of it would flap around like the patio door was open...

Ended up putting a piece of sanded and gloss painted wood about 50-60mm bigger than the air brick spaced on posts about 75mm off the internal wall to maintain the total airflow requirement. (At no point was the restriction *less* than about 15% more than the area of the air brick.)

Meant that we still had a cold corner, but that was right next to the patio door (so a bit cooler anyway) and the gas engineer was perfectly happy with it. Plus no howling gale across the top of your head while sitting on the sofa.
Actually used some modified IKEA coat handers so the whole thing just popped off (held on with o-rings on a spigot) when it needed a clean, the back of the board use to get covered in pollen/dust/grime fairly quickly.

Is there a way to interrupt the air flow on the outside of the vent to prevent it pulling air out of the house? For example if the prevailing wind is travelling along the wall and sucking air out can you put a panel of wood/metal perpendicular to the wall just before the vent to redirect the flow. Or, similar to mert has suggested (I think), if the wind blows directly in then a similar panel but offset flat from the wall by 100mm or so on upstands. Again, interrupts the air flow direction but doesn't change the actual vent size and still allows airflow to be sucked in to the house.

Block up the upstairs air brick and get trickle vents and/or intermittent extractors upstairs at sufficient air volume (to match the volume in m3/hr or l/s of the kitchen air brick).
I don't see why your boilerman should object provided your means of extraction is equal to the air entering the property.

Your boiler man would or should object if the ventilation does not meet the required standard. Trickle vents and hot and miss vents do not comply.

In this country we generally legislate by disaster, ie something went wrong, we need to amend or create regulation to prevent it from happening. Ventilation requirements came about from CO deaths I suspect as building changed and became more airtight. The recently reviewed the adventitous ventilation allowance as buildings are even more air tight than previously.

Bear
Please can you qualify your opening statement. What is the required standard? Do not comply with what? I work in the industry and have part F in front of me. Unless there are some special considerations required for hot air systems, then trickle vents provides adequate background ventilation. Plus, the building is not a new build.

Gas safety installation and use regulations.

It is a gas appliance and needs to be installed according to those, I think you are referring to approved document F which I don’t know as well but I believe they deal with building ventilation more than combustion ventilation.

I will have a look later when I get near a computer.

Unless there are some special considerations required for hot air systems, then trickle vents provides adequate background ventilation

It's an old fashioned open flue boiler, nothing to do with the fact it's blown air heating. Intermittent extractors are doing the opposite of ensuring the boiler has an air supply and would not be fail safe anyway.

Veganrider - Approved Document J covers ventilation for combustion.

PArt F ? This falls under part J combustion appliances

specifically 1.4 and the term is perminantly open ventilation - hit and miss and trickle vents not permitted.

I have had my boiler relocated and have the remnants of this issue in my house..... Expanding foam did me a solid.

How ever i also had to open up others where my woodburner is for similar reasons.

Thanks Bear. I can't see anything about the need for an air brick for discharge. From viewing part J my understanding is the air brick near the boiler is required - for air supply. Then the boiler exhaust gases are discharged via the flue.
Hence, not sure why you'd need a first floor air brick, and my mention of general ventilation requirements.
Cheers

@mahowlett Is it a Johnson and Starley heater? I have one and it’s wonderful except for the fact that it has 2 pilot lights (one water heater, one air heater). After 22 years of having them lit, I discovered that having pilot lights running all year-round alone was 1/3rd of our gas usage.

Anyway. Take a look in your loft at the top of your return vent (if it’s like ours you’ll have a grill on the landing that allows the fan to suck the air back down to the heater). If the installation is like ours, there’s a little ‘periscope’ that pokes up into the loft and gives 100mm2 ventilation into the air return. I believe this is enough to cover the air requirements for the heater and I think the idea is that the air is drawn into the house through that and straight into the heater so you don’t get a cold draft.

Happy to help via email if above explanation is confusing.