Timber frame house (MMC), found mice in ceiling - advice needed

[Kuro507]

We are just in the process of purchasing a house thats built out of timber frame with concrete block and render outside. We exchange on Friday and I have signed a form to get early access to a key (its empty).

Unfortunately on Sat afternoon I heard chewing about the utility room. I have removed a access panel above the boiler pipes and some mouse droppings fell down.

Luckily I have some traps, so set those out with peanut butter on Sat evening and caught two mice. During Sunday I caught 2 more.

 

We now obviously ahve some converns about what they may have eaten and damaged!

 

The oil fed boiler has a issue with the central heating system depressurising. Last pressurised to 1 bar 3 weeks ago, back to zero on Sat. I repressurised on Sat and it was down to 0.8 (cold) on Sunday eve.

Obviously have a concern they may have chewed a plastic central heating pipe. 

Does anybody know how much water there could be between zero bar and 1 bar in a 4 bedroom central heating system? I would have thought it would be noticable if we lost quite a bit, either on a ceiling or wall? (Unless its under the downstairs floor....) Pipe tails to radiators are 15mm copper, no idea whats in the floor/ceiling though.

 

I have notified estate agent and Solicitor, no reponse back yet. We are due to complete on Wed!!

 

Concerned about any potential hidden damage to insualtion, wiring, as well as pipes.

Some upstairs windows had been left open to keep air fresh, its been empty for almost a year. So thats a potential route in for them.

 

Any advice or suggestions are welcome, especialy with such a tight timescale to completion.

 

[ProDave]

Mice only need a tiny hole to get in, about the size of a hole in an air brick.  If it is a normal cold loft it will be ventilated and the standard sized vents will allow a mouse in.  Not much you can do but traps, poison and get a cat.  This is not a problem unique to timber frame.

 

If there are no obvious signs of water damage all you can do is keep topping up the heating pressure and see if anything develops.  Is is solid floor or suspended timber floor downstairs?  If suspended are there any access traps to the under floor space?

 

If it only loses pressure when the heating comes on and then goes off, it is equally possible the expansion vessel has failed and water is getting expelled via the discharge pipe each time it heats up.

[saveasteading]

10 minutes ago, ProDave said:

traps, poison and get a cat. 

Up in the attic I found the remains of a plastic tub of poison blocks. Mice (and/or rats) had chewed their way in, eaten the remaining  poison, then eaten the lid of the tub, which was like lace.

We don't appear to have mice or rats at present.

[Alan Ambrose]

I think you'll need a sum put aside by the vendor (or knocked off the price) for the two issues. Or delay until the vendor has fixed both.

 

>>> Does anybody know how much water there could be between zero bar and 1 bar in a 4 bedroom central heating system?

 

Water isn't compressible much:

 

... 4×10−5 per unit atmospheric pressure i.e. bar.

 

So if your heating system has say 8 off 10l radiators, then that's 80 x 4 x 10^-5 x 1 ~= 3ml i.e. a small teaspoon worth.

i.e. quite a small leak, say one that you might see dripping v slowly or detect slight wetness on a pipe.

I might go around checking all the valves, pipes, bleed nipples and see whether any are at all damp. Of course, if the water is hot, it'll evaporate reasonably fast.

 

If you like, you could get a plumber to pressure test the system in sections until they find the culprit.

 

 

[Kuro507]

45 minutes ago, Alan Ambrose said:

I think you'll need a sum put aside by the vendor (or knocked off the price) for the two issues. Or delay until the vendor has fixed both.

 

>>> Does anybody know how much water there could be between zero bar and 1 bar in a 4 bedroom central heating system?

 

Water isn't compressible much:

 

... 4×10−5 per unit atmospheric pressure i.e. bar.

 

So if your heating system has say 8 off 10l radiators, then that's 80 x 4 x 10^-5 x 1 ~= 3ml i.e. a small teaspoon worth.

i.e. quite a small leak, say one that you might see dripping v slowly or detect slight wetness on a pipe.

I might go around checking all the valves, pipes, bleed nipples and see whether any are at all damp. Of course, if the water is hot, it'll evaporate reasonably fast.

 

If you like, you could get a plumber to pressure test the system in sections until they find the culprit.

 

 

I love a technical explanation with numbers  Thankyou!

 

In my head I was expecting it to have to be a few litres!

In simple terms, if I needed to turn on the filling loop for 20 secs to bring it back to pressure, I would have guessed that would be a few litres based on how much water would come out of a tap in those 20secs.

 

There are 2 water marks on the ceiling, however they have been there for some time - saw them on initial viewing and both below bathrooms so

assumed they were sealant or waste leaks.

Based on your numbers, I think they are the likely cuprits then. Certainly a good place to start!

 

Thankyou again