House not getting hot enough?

[rosco14]

for some reason my house is never getting hot.....

I have a Potterton Flamingo 40 boiler with a Grunfos UPS 15-15 pump for the central heating system. I have 7 K2 radiators (recently changed by myself in place of the old single panel rad's) in a mid terrace house and never feel that the house heats up as much as it should do.

I would reckon since changing over the rad's from the old style single panel ones that the pump is now stretched and it takes a little while for the rads to heat up, but after being on for a few hours I would expect all rooms to get very warm? Each room has a honeywell Thermostatic Rad valve and it is turned up to 6!

A good example is in the bedroom. Rad is spec'd to give out approx 6000 BTU's and using an online calculator it reckons that the room only requires 4500 BTU's. The room is never overly warm

Can anyone give me a heads up?

Cheers

 

[scatmanjohn]

How hot are the rads getting?

I mean....can you put your hand on them?

 

[rosco14]

You can keep your hands on them but they are now getting pretty hot - that was til the pilot light decided to go out randomly and wouldnt come back on regardless!!

Got a guy in to fix that - now the boiler wont fire up at all so getting him back to sort that, and hopefully he can shed some light on the temp issue.......

Cheers

 

[giblets]

Just out of interest, before the pilot problem, what was the boiler thermostat set to?

 

[JohnD]

I had a Flamingo until recently, it was 15kW output (I don't do BTUs)

If your house is well-insulated it is enough for an average-size. Before I had my cavity walls filled it was insufficient. If your loft insulation is poor it is well-nigh impossible to get upstairs rooms warm enough.

If I guess that your rads are in the region of 1.5kW to 2 kW each, and you do not have such a lot of rads that they are beyond the capacity of the boiler...

how many have you got? and what do you calculate the kW load of all the rads to be?

have you an opinion of free-flow of the circulating water? if you put your hand on the pipes, you should find the Flow is "too hot to hold" and the return is "too hot to hold for long"

the things I would be looking for are:
this is an old system so there may be obstructions in the pipes, so the boiler reaches temp and cuts off while the rads are not fully hot. turning the pump speed to max will help, but you need to clean them out.

or

the 3-port valve or whatever is allowing excessive flow to the cylinder, so that not enough is going to the rads, this is quite common with age, but you will detect it by finding the cylinder primaries are hot even when cyl stat is satisfied. Sometimes a bathroom rad is plumbed before the valve and unless throttled down will steal a lot of flow.

or

your rad valves are not sufficiently open (lockshields too tight, or TRVs jammed)

or

your system needs balancing, and you have some rads that are taking too much flow so preventing it getting to the others.

a lot of this you can get a fair idea of by feeling the F&R pipes at the rads, pump, 3-port, and anywhere else you can reach them.

BTW you say you changed rads recently, I hope you gave the system a chemical clean as well as flushing it out.

I am just a householder

 

[neelpeel]

Before you do anything else...insulate, insulate, insulate!

As JohnD says, loft is most important. Also check around skirting and windows for draughts.