Just moved in and a massive water 💦 but please help me with the boiler!

jonnydeppiwish!

As the title, house has been empty for a year. Turned the water on to flush the loo and carried on unpacking. About 20mins later, heard this odd dripping. Went into the attic and found that the ball c£&@ valve had broken and water was cleaning the inside of the tiles.
quick trip to screwfix and £10, problem solved.

Anyway, back to the topic at hand.

There’s a 10 year old ideal boiler, tank and header tank. I have to remove the rads throughout to allow for insulation on exterior walls plus skim throughout.

Will the hot water still work if I drain the heating side?

Thanks in advance!

ThisIsWeird

Oops! So the overflow pipes from the loft tank didn't cope? That's bad news.

What type of boiler - combi, or hot cylinder?

FreeBear

ThisIsWeird said: What type of boiler - combi, or hot cylinder?

With a header tank, quite likely a gravity DHW tank. Unlikely that it could be run for just DHW without doing some temporary modifications to the plumbing.

With a combi boiler, one can usually turn the valves to closed on the CH flow & return pipes underneath the boiler before draining the CH side. The boiler would still be able to heat the hot water.

ThisIsWeird

If it's a heat-only boiler with a hot cylinder, then, as seems to be the likelihood, draining the CH will also drain the boiler and the heating coil for the hot tank.
So, to drain just the radiators, I think you'd have to temporarily disconnect and cap off the flow and return pipes to the rads, and then refill just the boiler and DHW loop.
Not a DIY task unless you are competent at disconnecting, possibly cutting, and then capping pipes.
If it's a combi boiler - unlikely as FreeBear points out - then in theory you could just turn the isolating valves to the CH which are underneath the boiler, since the CH and instant DHW are quite separate. But I'd first ask the boiler manufacturer if this is ok - will the boiler be happy running like this.

Albermarle

Does the hot water tank have a back up electric immersion heater ?

jonnydeppiwish!

Hi

its a conventional boiler with an immersion heather. I’m quite happy with pipework and capping off (that’s what speedfit was invented for!).

Its more of a temporary fix whilst we wait for a new combi to be fitted as that’s going to be 5 weeks, but I need to remove the rads for a full replaster, external wall insulated plasterboard etc.

thanks 

ThisIsWeird

In which case, you need to ID the motorised valve that serves the CH, either a single 3-porter, or one of two 2-porters, and cap off the flow to the CH. 
Then find the return from the CH, and ditto before it joins the DHW's return. 
Jobbie jobbed.

FreeBear

jonnydeppiwish! said: Its more of a temporary fix whilst we wait for a new combi to be fitted as that’s going to be 5 weeks, but I need to remove the rads for a full replaster, external wall insulated plasterboard etc.

Something to think about if you are insulating the walls - There is no real need to mount radiators under windows assuming they are double/triple glazed and free from cold draughts. This means you can hang them on internal walls and rationalise the plumbing in the process. Did this with my CH system last year as part of a new boiler install. Plumbing was done with an eye to the future when heat pumps are the only option. So 22mm feed & return, with the minimum of 15mm to the radiators. It will save having to rip up floorboards again

Also a good idea to increase the size of the radiators where you can - This means you can run with lower flow/return temperatures and get better efficiency out of the boiler.

jonnydeppiwish!

Update:

So had my BiL over today (Gas Safe man). He said the boiler is only 2 years old so refused to replace it (fair call). We are going to replace the tank with an unvented tank and remove the header tank etc in the loft.

Great results as saved probably £1500 so perfect MSE methods.

He also isolated the gas so I could remove the old fire place and oven connections and now there’s only one pipe leaving the meter, going through a wall and straight into the boiler.

Good day overall, now to decide if we want to replace all the rads with better looking ones 

FreeBear

jonnydeppiwish! said: Good day overall, now to decide if we want to replace all the rads with better looking ones 

If you are going to replace the radiators, crunch the numbers on this calculator -> https://www.stelrad.com/basic-heat-loss-calculator/ Then run the same numbers using a Delta T of 40°C - Going larger on the radiators means you can run at a lower flow temperature and get higher efficiency from the boiler.

Should you want to fit a heat pump in the future, try a Delta T of 30°C or even 15°C.