Hello Chaps

Am thinking of putting in an offer for a small ground floor flat, currently it has no heating. Am trying a few quick replans on paper and am wondering the following:

– At present the property has no gas connection, if I went with an electric water heater can anyone tell me if the heater needs direct venting to the outside, and if so can this vent be ducted horizontally over a distance?

– Are electric water heaters considered cost prohibitive these days?

– For a gas boiler, if situated internally can the vent be ducted horizontally to an outside wall and if so is there a maximum duct length?

Not the most exciting thread today I know!

Electric boiler won’t need a vent.
Electric will cost you over double per Kwh of heat.
Modern gas boilers are usually mounted on an external wall & ducted out the back.

Snaps – thank you. I thought as much.

Just leaves the query for a gas boiler what is the maximum horizontal duct length allowable as I don’t want to situate the boiler on an external wall.

Depends on the boiler.

Usually you’ll get around 5-7m using 60/100 concentric flue but bear in mind that each 1m of flue will cost around £40+vat for materials. Also, if you need to go around corners each 90deg elbow usually take 1m off the distance you can go with the flue. You can go further with a 100/125 flue system but it is a lot more expensive.

Look at the boiler specs, each boiler will have a Maximum Flue Length. They aren’t all the same.

Baxi always seemed to have decent allowable limits compared to others though, so maybe start there.

Don’t forget to factor in bends though when working it out. the first bend is ‘free’ then a one metre reduction for each 90 degree bend and half a metre reduction for each 45 degree bend.

Edit- crossed posts with above 🙂

And you can’t vent your boiler onto someone elses land either (must be at least 600mm away from the boundary).

What does it have at present?

Might be better looking at storage heaters/economy 7 system.

Look at the boiler specs, each boiler will have a Maximum Flue Length. They aren’t all the same.

Yup – had to look this up recently, our boiler is hopefully being moved to the middle of the ground floor with (potentially) a vertical flue to the roof.

With the “small” pipes maximum vertical flue is 12 metres. Goes to 30+ with the “big” pipes.

A question since you boiler types are here, is it possible to vent the flue below the level of the boiler? We want the boiler on the ground floor, but could potentially vent under the floor to the front of the house.

Actually, having thought about it, that might look a bit rubbish, can you do it anyway?

A question since you boiler types are here, is it possible to vent the flue below the level of the boiler? We want the boiler on the ground floor, but could potentially vent under the floor to the front of the house.

Not an gas fitter (I just sell them) but I haven’t heard of it being done. Flues slope back towards to boiler so that the condensate runs back into the boiler and can be disposed of safely as it’s acidic.

Not an gas fitter (I just sell them) but I haven’t heard of it being done. Flues slope back towards to boiler so that the condensate runs back into the boiler and can be disposed of safely as it’s acidic.

That sounds like a good enough reason not to do it 🙂

Ta.

can you do it anyway?

As above. No you can’t. Horizontal or Vertical only because of the condensate.
Would be messy and not very pleasant otherwise.

A question since you boiler types are here, is it possible to vent the flue below the level of the boiler? We want the boiler on the ground floor, but could potentially vent under the floor to the front of the house.

It’s a terrible idea the hot gasses “want” to go up not down and the risk of water accumulation in the duct would be another reason.